Robotic catheter system

ABSTRACT

A robotic catheter system includes a controller with a master input device. An instrument driver is in communication with the controller and has a guide instrument interface including a plurality of guide instrument drive elements responsive to control signals generated, at least in part, by the master input device. An elongate guide instrument has a base, distal end, and a working lumen, wherein the guide instrument base is operatively coupled to the guide instrument interface. The guide instrument includes a plurality of guide instrument control elements operatively coupled to respective guide drive elements and secured to the distal end of the guide instrument. The guide instrument control elements are axially moveable relative to the guide instrument such that movement of the guide instrument distal end may be controlled by the master input device.

RELATED APPLICATION DATA

The present application is a continuation of U.S. patent applicationSer. No. 13/118,309, filed May 27, 2011, now issued as U.S. Pat. No.8,394,054 on Mar. 12, 2013, which is a continuation of U.S. patentapplication Ser. No. 11/073,363, filed Mar. 4, 2005, now issued as U.S.Pat. No. 7,972,298 on Jul. 5, 2011, which claims the benefit under 35U.S.C. §119 to U.S. provisional patent application Ser. Nos. 60/550,961,filed Mar. 5, 2004, 60/553,029, filed Mar. 12, 2004, 60/600,869, filedAug. 12, 2004, and 60/644,505, filed Jan. 13, 2005. The foregoingapplications are hereby incorporated by reference into the presentapplication in their entirety.

FIELD OF INVENTION

The invention relates generally to robotically controlled systems, suchas telerobotic surgical systems, and more particularly to a roboticcatheter system for performing minimally invasive diagnostic andtherapeutic procedures.

BACKGROUND

Robotic surgical systems and devices are well suited for use inperforming minimally invasive medical procedures, as opposed toconventional techniques wherein the patient's body cavity is open topermit the surgeon's hands access to internal organs. For example, thereis a need for a highly controllable yet minimally sized system tofacilitate imaging, diagnosis, and treatment of tissues which may liedeep within a patient, and which may be preferably accessed only vianaturally-occurring pathways such as blood vessels or thegastrointestinal tract.

SUMMARY OF THE INVENTION

In accordance with a general aspect of the invention, a robotic cathetersystem is provided. The system includes a controller having a masterinput device. An instrument driver is in communication with thecontroller, the instrument driver having a guide instrument interfaceincluding a plurality of guide instrument drive elements responsive tocontrol signals generated, at least in part, by the master input device.The system further includes an elongate guide instrument having a base,distal end, and a working lumen, the guide instrument base beingoperatively coupled to the guide instrument interface. The guideinstrument comprises a plurality of guide instrument control elementsoperatively coupled to respective guide drive elements and secured tothe distal end of the guide instrument. The guide instrument controlelements are axially moveable relative to the guide instrument such thatmovement of the guide instrument distal end may be controlled bymovement of the master input device. In some embodiments, an operativecontact sensing element is carried on the distal end of the guideinstrument.

In some embodiments, the system comprises an elongate sheath instrumenthaving a base, distal end, and a lumen through which the guideinstrument is coaxially disposed. In such embodiments, the instrumentdriver preferably includes a sheath instrument interface operativelycoupled to the sheath instrument base, wherein the instrument driver maybe configured such that the guide instrument interface is moveablerelative to the sheath instrument interface, whereby the guideinstrument is moveable axially relative to the sheath instrument. Thesheath instrument interface may further include a sheath instrumentdrive element responsive to control signals generated, at least in part,by the master input device, the sheath instrument comprising a sheathinstrument control element operatively coupled to the sheath instrumentdrive element and secured to the distal end of the sheath instrument,the sheath instrument control element axially moveable relative to thesheath instrument such that movement of the sheath instrument distal endmay be controlled by movement of the master input device. An outersurface of the guide instrument and a surface defining the sheathinstrument lumen may be jointly configured to limit rotational movementof the guide instrument relative to the sheath instrument.

The controller and instrument driver are preferably configured toindependently control the guide instrument drive elements andcorresponding guide instrument control elements in order to achieve adesired bending of the guide instrument distal end. In particular, thecontroller can determine a tensioning to be applied to a respectiveguide instrument control element based on a kinematic relationshipbetween the desired bending and a linear movement of the guideinstrument control element relative to the guide instrument.

In accordance with another aspect of the invention, a working instrumentmay be disposed through the working lumen of, and be axially movablerelative to, the guide instrument. By way of non-limiting examples, theworking instrument may be an ablation catheter, a guidewire, or aninstrument comprising one or both of a dialator and a needle.

The robotic catheter system may further comprises an imaging system anda display, each operatively coupled to the controller. By way ofnon-limiting examples, the imaging system may be an ultrasound imagingsystem, an optical imaging system, a fluoroscopic imaging system, acomputer tomography imaging system, or an MR imaging system. In oneembodiment, the imaging system includes an elongate imaging instrumentwith an operative imaging element on a distal portion thereof. Theimaging instrument is configured for placement in a body passage orcavity, the operative imaging element being configured for acquiringimages of the body passage or cavity, the imaging system beingconfigured for presenting the acquired images on the display. In certainembodiments of the invention, the controller determines a tensioning tobe applied to a respective guide instrument control element based ondata from the acquired images.

The robotic catheter system may further comprise a localization system,e.g., an ultrasound localization system or an electromagneticlocalization system, that is operatively coupled to the controller andconfigured to obtain position information of the guide instrument. Incertain embodiments of the invention, the controller determines atensioning to be applied to a respective guide instrument controlelement based on data from the localization system.

Other and further embodiments and aspects of the invention will becomeapparent upon review of the following detailed description in view ofthe illustrated embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of illustratedembodiments of the invention, in which similar elements are referred toby common reference numerals, and in which:

FIG. 1 illustrates a robotic surgical system in accordance with someembodiments;

FIG. 2 illustrates a robotic surgical system in accordance with otherembodiments;

FIG. 3 illustrates a closer view of the robotic surgical system of FIG.2;

FIG. 4 illustrates an isometric view of an instrument having a guidecatheter in accordance with some embodiments;

FIG. 5 illustrates an isometric view of the instrument of FIG. 4,showing the instrument coupled to a sheath instrument in accordance withsome embodiments;

FIG. 6 illustrates an isometric view of a set of instruments for usewith an instrument driver in accordance with some embodiments;

FIG. 7A-7C illustrate a method of using a drape with an instrumentdriver in accordance with some embodiments;

FIG. 8A illustrates an instrument driver and a set of instruments beforethey are coupled to each other;

FIG. 8B illustrates the instrument driver and the set of instruments ofFIG. 8A after they are coupled to each other;

FIGS. 9-12 illustrate different drapes in accordance with someembodiments;

FIG. 13 illustrates a sleeve in accordance with some embodiments;

FIG. 14 illustrates an axel mating with the sleeve of FIG. 13 inaccordance with some embodiments;

FIG. 15 illustrates a drape for use with an instrument driver inaccordance with other embodiments;

FIG. 16 illustrates a covering assembly for use with an instrumentdriver in accordance with some embodiments;

FIG. 17 illustrates an isometric view of an instrument in accordancewith other embodiments;

FIG. 18 illustrates a catheter member of the instrument of FIG. 17 inaccordance with some embodiments;

FIG. 19 illustrates a cross sectional view of the catheter member ofFIG. 18 in accordance with some embodiments;

FIGS. 20-24 illustrate cross sectional views of catheter members inaccordance with other embodiments;

FIG. 25 illustrates an isometric view of a spine in accordance with someembodiments;

FIG. 26 illustrates a side view of the spine of FIG. 25;

FIG. 27 illustrates another spine in accordance with other embodiments;

FIG. 28 illustrates a cross sectional view of the spine of FIG. 25;

FIG. 29 illustrates a close up view of the spine of FIG. 25 inaccordance with some embodiments;

FIG. 30 illustrates a close up view of the spine of FIG. 25 inaccordance with other embodiments, showing stress relief angles;

FIGS. 31-32 illustrate another spine in accordance with otherembodiments;

FIG. 33 illustrates an isometric view of an anchoring ring for use at adistal tip of a catheter member in accordance with some embodiments;

FIG. 34 illustrates a cross sectional view of the anchoring ring of FIG.32;

FIG. 35 illustrates a control element interface assembly in accordancewith some embodiments;

FIG. 35A illustrates an axel of the control element interface assemblyof FIG. 35;

FIG. 36 illustrates a drive engagement knob in accordance with someembodiments, showing the drive engagement knob coupled to the axel ofFIG. 35A;

FIG. 37 illustrates a control element pulley of the control elementinterface assembly of FIG. 35 in accordance with some embodiments;

FIG. 38 illustrates a side view of the control element pulley of FIG.37;

FIG. 39 illustrates a top portion of a guide instrument base inaccordance with some embodiments;

FIG. 40 illustrates a top view of the top portion of FIG. 39;

FIG. 41 illustrates an isometric bottom view of the top portion of FIG.39;

FIG. 42 illustrates a bottom view of the top portion of FIG. 39;

FIG. 43 illustrates an isometric view of a bottom portion of a guideinstrument base in accordance with some embodiments;

FIG. 44 illustrates a top view of the bottom portion of FIG. 43;

FIG. 45 illustrates an isometric bottom view of the bottom portion ofFIG. 43;

FIG. 46 illustrates a bottom view of the bottom portion of FIG. 43;

FIG. 47 illustrates an assembled instrument proximal end in accordancewith some embodiments;

FIG. 48 illustrates a see-through view of the assembled instrumentproximal end of FIG. 47;

FIG. 49 illustrates a rear view of the assembled instrument proximal endof FIG. 47;

FIG. 50 illustrates a front view of an instrument in accordance withother embodiments;

FIG. 51 illustrates a side view of the instrument of FIG. 50;

FIG. 52 illustrates a top view of the instrument of FIG. 50;

FIG. 53 illustrates a bottom view of the instrument of FIG. 50;

FIG. 54 illustrates a top view of the instrument of FIG. 50, showing atop view of a guide instrument base in accordance with some embodiments;

FIG. 55 illustrates an isometric view of a guide instrument base inaccordance with other embodiments;

FIG. 56 illustrates an isometric view of a guide instrument base inaccordance with other embodiments;

FIG. 57 illustrates an isometric view of an instrument in accordancewith other embodiments;

FIG. 58 illustrates a side view of the instrument of FIG. 57;

FIG. 59 illustrates an isometric view of the instrument of FIG. 57,showing a bottom portion;

FIG. 60 illustrates a close up view of the bottom portion of FIG. 59;

FIG. 61 illustrates another view of the bottom portion of FIG. 59;

FIG. 62 illustrates a see-through view of the bottom portion of FIG. 59;

FIG. 63 illustrates an isometric view of an instrument in accordancewith other embodiments;

FIG. 64 illustrates an isometric view of a bottom portion of theinstrument of FIG. 63;

FIG. 65 illustrates an instrument having two control element interfaceassemblies coupled to a sheath instrument in accordance with someembodiments;

FIG. 66 illustrates an isometric view of a bottom portion of theinstrument of FIG. 65;

FIG. 67 illustrates an instrument having a control element interfaceassembly coupled to a sheath instrument in accordance with someembodiments;

FIG. 68 illustrates an isometric view of a bottom portion of theinstrument of FIG. 67;

FIG. 69 illustrates an isometric view of an instrument having a controlelement interface assembly coupled to a sheath instrument in accordancewith other embodiments;

FIG. 70 illustrates an isometric view of a bottom portion of theinstrument of FIG. 69;

FIG. 71 illustrates an isometric view of an instrument having a controlelement interface assembly coupled to a sheath instrument in accordancewith other embodiments;

FIG. 72 illustrates an isometric view of a bottom portion of theinstrument of FIG. 71;

FIG. 73 illustrates an isometric view of the instrument of FIG. 71,showing a top portion placed above a bottom portion;

FIG. 74 illustrates an instrument coupled with a sheath instrument inaccordance with some embodiments;

FIG. 75 illustrates an isometric view of the sheath instrument of FIG.74;

FIG. 76 illustrates an end isometric view of the sheath instrument ofFIG. 74;

FIG. 77 illustrates a bottom isometric view of a bottom portion of thesheath instrument of FIG. 74;

FIG. 78 illustrates a top isometric view of the bottom portion of FIG.77;

FIG. 79 illustrates a bottom view of a top portion of the sheathinstrument of FIG. 74;

FIG. 80 illustrates a sheath catheter for use with a sheath instrumentin accordance with some embodiments;

FIG. 81 illustrates a cross sectional view of the sheath catheter ofFIG. 80 in accordance with some embodiments;

FIG. 82 illustrates a cross sectional view of another sheath catheter inaccordance with other embodiments;

FIG. 83 illustrates a cross sectional view of another sheath catheter inaccordance with other embodiments;

FIG. 84 illustrates a cross sectional view of another sheath catheter inaccordance with other embodiments;

FIG. 85 illustrates a cross sectional view of another sheath catheter inaccordance with other embodiments;

FIG. 86 illustrates a cross sectional view of a guide catheter insertedinto a lumen of a sheath catheter in accordance with some embodiments;

FIGS. 87-91 illustrate cross sectional views of guide catheters insertedinto respective sheath catheters in accordance with other embodiments;

FIG. 92 illustrates a sheath catheter member coupled to a seal and anaccess port in accordance with some embodiments;

FIG. 93 illustrates a side view of the sheath catheter member of FIG.92;

FIG. 94 illustrates an end view of the seal of FIG. 92;

FIG. 95 illustrates an instrument driver in accordance with someembodiments;

FIG. 96 illustrates an instrument driver in accordance with otherembodiments;

FIG. 97 illustrates an isometric view of an instrument driver coupledwith a steerable guide instrument and a steerable sheath instrument inaccordance with some embodiments;

FIG. 98 illustrates components of the instrument driver of FIG. 97 inaccordance with some embodiments;

FIG. 99 illustrates the instrument driver of FIG. 98, showing theinstrument driver having a roll motor;

FIG. 100 illustrates components of an instrument driver in accordancewith some embodiments, showing the instrument driver having four motors;

FIG. 101 illustrates a side view of components of an instrument driverin accordance with other embodiments;

FIG. 102 illustrates a cover plate covering components of an instrumentdriver in accordance with some embodiments;

FIG. 103 illustrates components of the instrument driver of FIG. 102;

FIG. 104 illustrates an operator control station in accordance with someembodiments;

FIG. 105A illustrates a master input device in accordance with someembodiments;

FIG. 105B illustrates a master input device in accordance with otherembodiments;

FIG. 106A illustrates kinematics of a catheter's first bend and FIG.106B illustrates a cross sectional view of the catheter, in accordancewith some embodiments;

FIG. 107A illustrates kinematics of a catheter's second bend and FIG.107B illustrates a cross sectional view of the catheter, in accordancewith some embodiments;

FIG. 108A illustrates kinematics of a catheter's third bend and FIG.108B illustrates a cross sectional view of the catheter, in accordancewith some embodiments;

FIG. 109A illustrates kinematics of a catheter's fourth bend and FIG.109B illustrates a cross sectional view of the catheter, in accordancewith some embodiments;

FIGS. 110A-110E illustrates different bending configurations of acatheter in accordance with various embodiments;

FIG. 111 illustrates a control system in accordance with someembodiments;

FIG. 112A illustrates a localization sensing system having anelectromagnetic field receiver in accordance with some embodiments;

FIG. 112B illustrates a localization sensing system in accordance withother embodiments;

FIG. 113 illustrates a user interface for a master input device inaccordance with some embodiments;

FIGS. 114-124 illustrate software control schema in accordance withvarious embodiments;

FIG. 125 illustrates forward kinematics and inverse kinematics inaccordance with some embodiments;

FIG. 126 illustrates task coordinates, joint coordinates, and actuationcoordinates in accordance with some embodiments;

FIG. 127 illustrates variables associated with a geometry of a catheterin accordance with some embodiments;

FIG. 128 illustrates a block diagram of a system having a haptic masterinput device;

FIG. 129 illustrates a method for generating a haptic signal inaccordance with some embodiments;

FIG. 130 illustrates a method for converting an operator hand motion toa catheter motion in accordance with some embodiments;

FIG. 131 illustrates a diagram representing an operation of the deviceof FIG. 102 in accordance with some embodiments;

FIG. 132 illustrates a set of equations associated with the diagram ofFIG. 131;

FIGS. 133-136 illustrate equations associated with an operation of aguide instrument interface socket in accordance with some embodiments;

FIG. 137 illustrates a localization device being used in a heart inaccordance with some embodiments;

FIG. 138 illustrates a cross sectional view of the heart of FIG. 137,showing the heart being imaged by a localization device in accordancewith some embodiments;

FIG. 139 illustrates images generated using the localization device ofFIG. 137;

FIG. 140 illustrates an ultrasound image acquisition device being usedto acquire a plurality of image slices in accordance with someembodiments;

FIG. 141 illustrates cavity threshold points obtained from the slices ofFIG. 140;

FIG. 142 illustrates a circumferentially-firing ultrasound catheterdevice in accordance with some embodiments;

FIG. 143 illustrates two views taken along a longitudinal axis of thecatheter device of FIG. 142 in accordance with some embodiments;

FIG. 144 illustrates mathematics for transforming position andorientation data from a local reference to a desired frame of reference;

FIGS. 145A-145B illustrate two views of a catheter being used to acquiredata slices in a tissue cavity in accordance with some embodiments;

FIGS. 146A-146D illustrate different configurations of a catheter beingused to acquire slice data within a tissue cavity;

FIG. 147 illustrates different bending configurations of a catheter inaccordance with some embodiments;

FIGS. 148A-148C illustrate different embodiments of a method forgenerating a three dimensional model of a tissue cavity;

FIG. 149 illustrates a method for acquiring a three-dimensional tissuestructure model in accordance with some embodiments;

FIG. 150 illustrates a method for acquiring a three-dimensional tissuestructure model in accordance with other embodiments

FIG. 151 illustrates an instrument having localization capability inaccordance with some embodiments;

FIG. 152 illustrates an instrument having two vibratory devices inaccordance with some embodiments;

FIG. 153 illustrates an instrument having tissue sensing capability inaccordance with some embodiments;

FIG. 154 illustrates the instrument of FIG. 153 being used on a patientin accordance with some embodiments;

FIG. 155 illustrates a circuit diagram associated with the instrument ofFIG. 153 in accordance with some embodiments;

FIG. 156 illustrates examples of various ECG signals;

FIG. 157 illustrates a signal processing technique for comparing anintracardiac ECG signal with a body surface ECG signal in accordancewith some embodiments;

FIGS. 158A-158D illustrate a method of moving a distal end of aninstrument from a first position to a second position in accordance withsome embodiments;

FIGS. 159A-159D illustrate a method of moving a distal end of aninstrument from a first position to a second position in accordance withother embodiments;

FIGS. 160A-160D illustrate a method of moving a distal end of aninstrument from a first position to a second position in accordance withother embodiments;

FIGS. 161-169 illustrate a method of using a robotically controlledguide catheter instrument and sheath instrument in an atrial septalapproach in accordance with some embodiments;

FIG. 170 illustrates a system having an instrument driver and anablation energy control unit in accordance with some embodiments;

FIG. 171 illustrates the instrument driver of FIG. 170, showing atherapeutic catheter inserted through a sheath catheter in accordancewith some embodiments;

FIG. 172 illustrates the instrument driver of FIG. 170, showing a guidecatheter inserted through a sheath catheter, and a therapeutic catheterinserted through the guide catheter in accordance with some embodiments;

FIG. 173A illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having two bipolarelectrodes;

FIG. 173B illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having two bipolarelectrodes spaced axially;

FIG. 173C illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having a monopolarelectrode;

FIG. 173D illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having a sidemonopolar electrode;

FIG. 174A illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having an energytransmitter;

FIG. 174B illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having a lasergenerator;

FIG. 174C illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having a needle;and

FIG. 174D illustrates a device inserted through a guide catheter inaccordance with some embodiments, showing the device having a tissuedisruption mechanism.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring to FIG. 1, one embodiment of a robotic surgical system (32),includes an operator control station (2) located remotely from anoperating table (22), to which a instrument driver (16) and instrument(18) are coupled by a instrument driver mounting brace (20). Acommunication link (14) transfers signals between the operator controlstation (2) and instrument driver (16). The instrument driver mountingbrace (20) of the depicted embodiment is a relatively simple,arcuate-shaped structural member configured to position the instrumentdriver (16) above a patient (not shown) lying on the table (22).

Referring to FIG. 2, another embodiment is depicted wherein a movablesetup mount (26) is configured to movably support the instrument driver(16) above the table (22) to provide convenient access to the desiredportions of the patient (not shown) and provide a means to lock theinstrument driver (16) into position subsequent to preferred placement.FIG. 3 provides a closer view of the embodiment depicted in FIG. 2,showing the movable setup mount (26) in further detail. In oneembodiment, the movable setup mount comprises a series of rigid linkscoupled by electronically braked joints (34) which prevent joint motionwhen unpowered, and allow joint motion when energized by a controlsystem, such as a switch or computer interface. In another embodiment,the rigid links may be coupled by more conventional mechanicallylockable joints, which may be locked and unlocked manually using, forexample, locking pins, screws, or clamps. The rigid links (36)preferably comprise a light but strong material, such as high-gagealuminum, shaped to withstand the stresses and strains associated withprecisely maintaining three-dimensional position of the approximatelyten pound weight of a typical embodiment of the instrument driver (16)sized or intravenous use subsequent to application of the brakes.

FIGS. 4 and 5 depict isometric views of respective embodiments ofinstruments configured for use with an embodiment of the instrumentdriver (16), such as that depicted in FIGS. 1-3. FIG. 4 depicts aninstrument (18) embodiment without an associated coaxial sheath coupledat its midsection. FIG. 5 depicts a set of two instruments (28),combining an embodiment like that of FIG. 4 with a coaxially coupled andindependently controllable sheath instrument (30). To distinguish thenon-sheath instrument (18) from the sheath instrument (30) in thecontext of this disclosure, the “non-sheath” instrument may also betermed the “guide” instrument (18).

Referring to FIG. 6, a set of instruments (28), such as those in FIG. 5,is depicted adjacent an instrument driver (16) to illustrate anexemplary mounting scheme. The sheath instrument (30) may be coupled tothe depicted instrument driver (16) at a sheath instrument interfacesurface (38) having two mounting pins (42) and one interface socket (44)by sliding the sheath instrument base (46) over the pins (42).Similarly, and preferably simultaneously, the guide instrument (18) base(48) may be positioned upon the guide instrument interface surface (40)by aligning the two mounting pins (42) with alignment holes in the guideinstrument base (48). As will be appreciated, further steps may berequired to lock the instruments (18, 30) into place upon the instrumentdriver (16).

In one embodiment, the instruments (18, 30) are provided for a medicalprocedure in sterile packaging, while the instrument driver (16) is notnecessarily sterile. In accordance with conventional sterile medicalprocedure, the nonsterile instrument driver (16) must be isolated fromthe patient by a sterile barrier of some type. Referring to FIGS. 7A-7C,a drape (50) comprising conventional surgical draping material may befolded into a configuration (52) to enable gloved hands of a person (notshown) to slide the drape (50) over the instrument driver (16), from oneend to the other without contamination of the sterile side of the drape(50). The drape (50) is then unrolled around the instrument driver (16),as shown in FIGS. 7B and 7C.

Referring to FIGS. 8A and 8B, the interfacing between instrument driver(16) and instrument bases (46, 48) utilizing alignment pins (42) isdepicted to further illustrate the issues associated with providing asterile barrier between the instruments and driver. In the illustratedembodiment(s), wherein the instrument is a set of two instrumentscomprising both a sheath instrument (30) and a guide instrument (18),the draping is preferably configured to accommodate relative motion (56)between the two instrument bases (46, 48). Further, the fit between theinstrument bases (46, 48) and pertinent alignment pins (42) preferablyis not loose and does not allow for relative motion. Similarly, theinterface between axels (54) extending from the instruments and sockets(44) comprising the instrument driver (16) preferably is a precisioninterface.

Referring to FIGS. 9-16, various embodiments of suitable draping schemasare depicted. As shown in FIG. 9, a perforated drape (58) may beutilized, wherein perforations (68) are sized to fit the alignment pins(42) and interface sockets (44). The perforated drape (58), preferablymade from conventional draping materials, is simply alignedappropriately and pulled down upon the instrument driver (16).

Referring to FIG. 10, a perforated drape with socks (60) may also beutilized. The depicted drape (60) has perforations (68) for theunderlying interface sockets (44), but has socks (70), also formed fromconventional draping material, which are sized to encapsulate themounting pins (42) of the instrument driver (16).

Referring to FIG. 11, the depicted drape (62) may comprise “socks” (70)to engage the mounting pins (42), as with the drape in FIG. 10, but alsohave integrated plastic sleeves (64) rotatably coupled to thesurrounding conventional drape material. The integrated plastic sleeves(64) are preferably precisely sized to engage both the interface sockets(44) of the instrument driver (16) and the axels (not shown) of aninstrument. The sleeves (64) are preferably constructed of asterilizable, semi-rigid plastic material, such as polypropylene orpolyethylene, which has a relatively low coefficient of friction ascompared with conventional drape material. To decrease rotationalfriction between the integrated plastic sleeves (64) and the surroundingdrape material, perforations in the drape material through which thesleeves (64) are to be placed may be circumferentially lined withplastic collars (not shown), comprising a material having a lowcoefficient of friction relative to that of the integrated plasticsleeves (64).

Referring to FIG. 12, an embodiment similar to that of FIG. 11 isdepicted, with the exception that removable plastic sleeves (66) are notintegrated into the drape, as delivered and unwrapped. Instead, thedrape (60) may be delivered with perforations (68), circumferentiallylined in one embodiment with plastic collars (not shown), positioned forconvenient drop-in positioning of the sleeves (66). FIG. 13 is a closeup view of a plastic sleeve (66) suitable, for example, in theembodiment of FIG. 12. The sleeve (66) may also be integrated into theembodiment depicted in FIG. 11. FIG. 14 illustrates that the inside ofthe sleeve (66) may be fitted to engage an axel (54) extending down froman instrument body.

Referring to FIG. 15, another draping embodiment is depicted, whereintwo semi-rigid covers or plates (72) are incorporated into a largerpiece of conventional draping material. The covers (72) are configuredto snap into position upon the sheath instrument interface surface (38)and guide instrument interface surface (40), fit over the mounting pins(42), and provide relatively high-tolerance access to the underlyinginterface sockets (44), with pre-drilled holes (76) fitted for thepertinent drive axel structures (not shown). Due to the anticipatedrelative motion between the two instrument interfaces, as previouslydescribed with reference to FIGS. 8A and 8B, it may be preferable tohave elastic draping material or extra draping material bunched orbellowed in between the two interfaces, as shown in FIG. 15, andsimilarly applicable to the embodiments of FIGS. 9-14.

Referring to FIG. 16, another semi-rigid covering embodiment comprises asemi-rigid covering for the entire local surface of the instrumentdriver (16), without conventional draping in between semi-rigidsub-pieces. To accommodate relative motion, high tolerance overlapsections (78) are provided with sufficient overlap to allow relativemotion without friction binding, as well as gapping of sufficienttightness that the sterility of the barrier remains intact. Thesemi-rigid covers of the embodiments of FIGS. 15 and 16 may be molded ormachined from polymeric materials, such as polycarbonate, which areinexpensive, sterilizable, somewhat flexible for manual snap-oninstallation, and fairly translucent to facilitate installation andtroubleshooting.

FIG. 17 is an isometric view of one embodiment of an instrument (18)configured for instrument steering via independent control of fourcatheter control elements, or four tension elements, such as cablescomprising materials, e.g., stainless steel. The proximal portion (82)comprises a guide instrument base (48) and four axels (54) withassociated manual adjustment knobs (86). The middle (84) and distalportions (87) comprise a catheter member which extends into the guideinstrument base (48) forming part of the proximal portion (82).

Referring to FIG. 18, a catheter member (90) is depicted having controlelement apertures (92) through the proximal portion (88) of the cathetermember to accommodate control elements (not shown), such as tensioncables. The control elements may be disposed along the length of thecatheter member (90), and positioned to exit the catheter through theapertures (92) and into association with other structures comprising theproximal portion (82) of the instrument. The proximal (88) and middle(84) portions of the catheter member (90) are shown in a substantiallystraight configuration, which is preferred for controllability of themore flexible distal portion (87). Indeed, the proximal (88) and middle(84) portions are structurally reinforced and made from stiffermaterials to enhance torque transmission and insertability to the distalportion, while also providing enough cantilever bendability tofacilitate access to remote tissue locations, such as the chambers ofthe heart.

FIG. 19 is a cross sectional view of the catheter member (90) at eitherthe proximal (88) or middle (84) portion. At the center of the crosssectional construct is a central (or “working”) lumen (108), thegeometry of which is selected in accordance with the requisite medicalapplication. For example, in one embodiment it is desired to pass acommercially available ablation catheter having an outer diameter ofabout 7 French through the working lumen (108), in which case it ispreferable to have a working lumen in the range of 7 French in diameter.The catheter member (90), and the entire system (32), for that matter,can be sized up or down in accordance with the desired procedure andtools. The proximal portion of the catheter member (90) may bereinforced with a stiffening member such as a braiding layer (98) whichis preferably encapsulated on the outside by an outer layer (96) havingat least one lumen (102) to accommodate a control element, such as atension cable (not shown), and a low-friction inner layer (100) selectedto provide a low-friction surface over the inside of the braiding layer(98). Four extruded lumens (102) are provided in the illustratedembodiment to accommodate four respective control elements (not shown).

To prevent relative rotational motion between the catheter member (90)and other structures which may surround it, the profile of the outerlayer adjacent the control element lumens (102) may be increased. Thecross section of the embodiment of FIG. 19 has a relatively low surfaceprofile (104) adjacent the control element lumens (102), as comparedwith the cross section of the embodiment of FIG. 20, which is otherwisesimilar to that of FIG. 19. Indeed, within the same catheter member, itis preferable to have a more pronounced surface profile distally tointerface with surrounding structures and prevent “wind up”, ortorsional rotation, of the distal and middle portions of the cathetermember. With the braiding layer (98) in the middle (84) and proximal(82) portions of the instrument, “wind up” is not as significant anissue, and therefore it is less important to have a pronounced surfaceprofile to interface or “key” with other adjacent structures.

FIG. 21 depicts an embodiment having three control element lumens (102)disposed approximately equidistantly from each other about the perimeterof the catheter member (90) cross section. This embodiment illustratesby way of non-limiting example that the catheter member (90) need not belimited to configurations comprising four control element lumens or fourcontrol elements. By way of another example, FIG. 22 illustrates anon-equidistant, three-lumen (102) configuration, with two-lumen (102)and single lumen (102) variations shown in FIGS. 23 and 24,respectively.

To facilitate more dramatic bendability at the distal portion (87) ofthe catheter member (90), a reinforcing structure other than a braidinglayer may be preferred. By way of non-limiting example, FIGS. 25-27depict a metal spine (110) having a unique stress relief geometry cutinto its walls. FIG. 28 depicts a cross section of an embodiment of ametal spine (110) to illustrate that the working lumen may be continuedfrom the proximal (88) and middle (84) portions of the catheter memberinto the distal portion (87) through the center of the metal spine(110). Indeed, the metal spine preferably has similar inner and outerdiameter sizes as the braiding layer (98) in the more proximal portionsof the catheter member (90). Depending upon the metal utilized for themetal spine (110), very tight bend radius operation of the distalportion (87) of the catheter member (90) is possible, due in significantpart to such a highly bendable reinforcing structure and its associatedrepeated stress relief pattern. To further enhance the flexibility ofthe distal portion (87) of the catheter member (90), softer polymericmaterials may be utilized in the construct, such as Pebax™. For example,in one embodiment, the outer layer (96) in the proximal (88) and middle(84) portions of the catheter member (90) preferably comprise 70durometer Pebax™, while in the distal portion (84) and outer layer (96)preferably comprise 35 or 40 durometer Pebax™.

Referring to FIGS. 29 and 30, one embodiment of a stress relief patternis depicted in close-up view to illustrate that the pattern may beshifted by about ninety degrees with each longitudinal step along thespine (110) to maximize the homogeneity of stress concentration andbending behavior of the overall construct. To further enhance theflexibility of the metal spine, and clean up undesirable geometricdiscrepancies left behind after laser cutting, the metal spine may bechemically etched and electropolished before incorporation into thecatheter member (90). As shown in FIG. 30, chemical etching takes thepattern from the original lasercut positioning (114) to a revisedpositioning (112) with larger windows in the pattern. In thisembodiment, subsequent to chemical etching, the pattern forms a reliefangle with sides (116 a-116 b, 118 a-118 b) with an intersection (120)and included angle (122). Preferred metal spine materials include, butare not limited to, stainless steel and nitinol.

Referring to FIGS. 31 and 32, the distal reinforcing structure may alsocomprise a polymeric spine (124) similarly configured to homogeneouslybend due to a stress relief pattern comprising the tubular wall of thespine (124). In particular, due to the greater fracture toughnesses ofmany available polymeric materials, a more squared stress concentratingpattern may be repeated with polymer structures. Further, high-precisionstructures such as the depicted polymeric spine (124), may be formedusing injection molding and/or other techniques less inexpensive thanlaser cutting and etching. As will be apparent to those skilled in theart, many other distal spine structures for concentrating and relievingstress may also be utilized to provide the requisite tight bend radiusfunctionality distally within the catheter member (90) construct,including but not limited to coils and braids.

Referring to FIG. 33, a control element anchoring ring (126) is depictedhaving two anchoring lumens (128) for each incoming control element tobe anchored at the distal tip of the catheter member (90). The anchoringring (126) comprises the last rigid construct at the distal tip of thecatheter member (90), beyond which only a low durometer polymericatraumatic distal tip (not shown) extends, as the low friction liner(100) meets the outer layer (96) subsequent to these two layersencapsulating the anchoring ring (126). The anchoring ring (126) is the“anchor” into which the relatively high-tension control elements arefixedly inserted—and is therefore a key to the steerability andcontrollability of the catheter member (90) regardless of the number ofcontrol elements pulling upon it. In one embodiment, tension wirecontrol elements (not shown) insert into the outermost of the anchoringlumens, then bend directly back into the innermost of the anchoringlumens, where they are soldered to the anchoring ring, which comprisemachined or gold plated stainless steel for solderability.

FIGS. 35-49 depict certain aspects of a proximal portion (82) of aninstrument (18) similar to that depicted in FIG. 19. Referring to FIG.35, a control element interface assembly (132) is depicted, comprisingan axel (54), a control element pulley (136), a manual adjustment knob(86), and a drive engagement knob (134). The manual adjustment knob isconfigured to facilitate manual adjustment of control element tensionsduring setup of the instrument upon the instrument driver. It is held inplace against the axel (54) with a clamp screw (138), and houses arotation range of motion limitation pin (140) which limits the range ofmotion of the axel subsequent to setup and tightening of the clampscrew. Referring to FIG. 35A, one embodiment of an axel (54) is depictedin isometric view without other hardware mounted upon it. Referring toFIG. 36, an axel (54) is depicted with a drive engagement knob (134)mounted upon it. The drive engagement knob (134) may take a shapesimilar to a screw with a long threaded portion configured to extendthrough the axel to engage a tapered nut (142), as shown. Twisting ofthe drive engagement knob (134) causes the tapered nut (142) to urge theteeth (144) of the axel outward, thereby engaging whatever structuressurround the lower portion of the axel, including but not limited to ainstrument driver interface socket (44).

FIGS. 37 and 38 depict respective orthogonal views of one embodiment ofa control element pulley (136). The central hole (148) in the pulley(136) is sized for a press fit upon an axel, and the control elementtermination engagement slot (146) is configured to capture a controlelement terminator, such as a lead or steel cable terminator, that ispushed into the slot before a control element is wound around the pulley(136) during manufacture or rebuilding. Referring to FIG. 38, the pulley(136) preferably has a flanged shape (150) to facilitate winding andpositional maintenance of a control element.

As shown in FIG. 39, the top portion (152) of one embodiment of a guideinstrument base (48) comprises slots (154) to interface with therotation range of motion limitation pins (140), which may be housedwithin a manual adjustment knob (86). FIG. 40 depicts a top view of thetop portion (152). FIG. 41 depicts the same top portion (152), as viewedisometrically from underneath, to demonstrate how two pulleys may bemounted in related to the top portion (152) of the guide instrument base(48). The control element splay tracks (158) are employed to guidecontrol elements (not shown) from apertures in a catheter member intopulleys which may be positioned within the pulley geometryaccommodations (160) formed into the top portion (152) of the guideinstrument base (48). Also shown in the top portion (152) is a cathetermember geometry accommodation (162) and a seal geometry accommodation(164). FIG. 42 depicts an orthogonal view of the structures of FIG. 41to better illustrate the control element splay track (158) structurespositioned to guide control elements (not shown) away from a cathetermember and over to a pulley associated with the top portion (152) of theguide instrument base (48).

Referring to FIG. 43, a bottom portion (156) of one embodiment of aguide instrument base (48) is configured to interface with a top portion(152) such as that depicted in FIGS. 39-42. The bottom portion (156) hastwo additional pulley geometry accommodations (160) and associatedcontrol element splay tracks (158). The top (152) and bottom (156)portions of the guide instrument base (48) are “sandwiched” together tocapture the proximal portion (88) of a catheter member (90), andtherefore the bottom portion (156) also has a catheter member geometryaccommodation (162) and a seal geometry accommodation (164) formed intoit. FIG. 44 depicts an orthogonal view of the structures of FIG. 43 tobetter illustrate the control element splay track (158) structurespositioned to guide control elements (not shown) away from a cathetermember and to a pulley associated with the bottom portion (156) of theguide instrument base (48). FIG. 45 depicts an underside isometric viewof the same bottom portion (156) shown in FIGS. 43 and 44. The bottomsurface may comprise magnets (166) to facilitate mounting of theinstrument upon an instrument driver. The depicted embodiment also hasmounting pin interface holes (168) formed through it to accommodatemounting pins from an instrument driver. Further, the bottom surfacepreferably has a generally asymmetric geometry to ensure that it willonly fit an underlying instrument driver snugly in one way. FIG. 46depicts an orthogonal view of the bottom portion (156) of the guideinstrument base (48) embodiment of FIG. 45.

FIG. 47 illustrates a partially (although nearly completely) assembledinstrument proximal end (82), including a top portion (152) and bottomportion (156) of an instrument base (48) interfaced together. Theproximal end (82) houses four pulleys (not shown), a catheter member(90), and a seal (170), including and a purging port (172). Three manualadjustment knobs (86) are mounted to the guide instrument base (48) byaxels (54), which are held in place by pulleys (not visible) mountedupon the axels (54). Rotational range of motion limitation pins (140)interface with the manual adjustment knobs and slots (154) in the guideinstrument base (48) top portion (152). One of the four manualadjustment knobs is removed from the embodiment in FIG. 47 to illustratethe interaction between the pin (140) and slot (154). FIG. 48 shows thelocations of the pulleys (136) and control element splay tracks (158)within this four-control element embodiment. Control elements (notshown) preferably comprise solid wires made from materials such asstainless steel, which are sized for the anticipated loads and geometricparameters of the particular application. They may be coated withmaterials such as Teflon™ to reduce friction forces. FIG. 49 illustratesa different isometric view of an instrument embodiment similar to thatin FIG. 47 to better illustrate the seal (170) and purging port (172)positioning, as well as the clamp screws (138) of the manual adjustmentknobs (86). The seal (170) preferably comprises a silicon rubber sealconfigured to accommodate insertion of working members or instruments,such as, e.g., relatively small profile guidewires (e.g, in the range of0.035″ diameter), or relatively larger profile catheters (e.g., of up to7 French or even larger).

Referring to FIGS. 50-73, other embodiments of instruments are depictedhaving the respective capabilities to drive two, three, or four controlelements with less than four control element interface assemblies (132)as previously discussed. For ease in illustration, many of the samecomponents are utilized in these embodiments. As will be appreciated bythose skilled in the art, such component matching is by no meansrequired to accomplish the described functions, and many alternativearrangements are possible within the scope of the inventions disclosedherein.

FIGS. 50, 51, and 52 illustrate an instrument (174) having two controlelement interface assemblies (132) is depicted in three orthogonalviews. While this embodiment has only two control element interfaceassemblies, it is configured to drive four control elements and keepthem in tension through either pre-tensioning, or active tensioningthrough a slotted guide instrument base (188) to a tensioning mechanismin the instrument driver (16). FIG. 53 illustrates an instrument (174)similar to that in FIG. 52, but shown from a back or bottom sideorthogonal view. In particular, one side of the guide instrument base(188) forms slots (190) through which an instrument driver tensioningmechanism may keep control elements taut during operation of theinstrument (174). FIG. 54 is a reverse orthogonal view of the structurein FIG. 53, with one side of the guide instrument base, and both controlelement interface assemblies, removed (132) to show the slots (190) andfour control elements (192).

FIG. 55 illustrates an instrument (175) similar to that in FIGS. 53 and54, with the exception that the guide instrument base (194) does nothave slots—but rather has only fixed idler control element pathways toalign the cables with the sets of two pulleys (136) comprising eachcontrol element interface assembly (132). In this embodiment, tensionmay be maintained in the control elements (192), with pre-tensioning, orpre-stressing, to prevent control element slack. FIG. 56 alsoillustrates an instrument (174) similar to that of FIGS. 53 and 54,including slots to allow for active tensioning of the control elements(192) from the underlying instrument driver. One of the control elementinterface assemblies (132) is shown intact, and one is shown onlypartially intact, with the axel (54) and drive engagement knob (134)depicted to show the control elements (192). A notable differencebetween the embodiment in FIG. 56 and that in FIG. 55 is the addition ofthe tensioning slots (190).

Referring to FIGS. 57 and 58, yet another instrument embodiment (176) isdepicted in isometric and side views, respectively, with this embodimenthaving two control element interface assemblies to drive four controlelements. As shown in the partial cutaway isometric view of FIG. 59, andclose up cutaway view of FIG. 60, this embodiment differs from the fixedidler embodiment of FIG. 55, or the slotted embodiment of FIG. 56, inthat it has four spring-loaded idlers to assist with tensioning each ofthe four control elements. Referring to FIG. 60, each of the controlelements (192) passes through a spring loaded idler (198), which urgesthe control element (192) into tension by trying to rotate (200). Thistensioning schema may be easiest to visualize in the orthogonal cutawayview of FIG. 61, wherein the spring loaded idlers (198) are depictedurging (200) the four control elements (192) into tension. The wireframeorthogonal view of FIG. 62 also shows the stacks of two pulleys each oneach control element interface assembly (132) to accommodate fourcontrol elements (192).

FIGS. 63 and 64 depict another instrument embodiment (178), this onehaving three control element interface assemblies (132) for threeindependent control elements. As best seen in FIG. 64, this embodimentis similar to that of FIG. 47, for example, except that it has one lesscontrol element and one less control element interface assembly (132).FIG. 65 depicts yet another instrument embodiment (180) coupled with asheath instrument (30). In particular, instrument (180) has two controlelement interface assemblies (132) and two control elements. As bestseen in FIG. 66, the instrument (180) is not configured for slottedtensioning or spring-loaded tensioning. Instead, the control elements(192) of this embodiment may be actively tensioned independently, and/orpre-tensioned, to facilitate maintenance of tension for controlpurposes.

Referring to FIG. 67, yet another instrument embodiment (182) is showncoupled with a sheath instrument (30). Instrument (182) has a singlecontrol element interface assembly (132) and two control elements. Asbest seen in FIG. 68, instrument (182) is also not configured forslotted tensioning or spring-loaded tensioning. Instead, the controlelements (192) of this embodiment may be pre-tensioned and kept inposition with the help of a fixed idler control element pathway (196) tofacilitate maintenance of tension for control purposes. FIG. 69illustrates still another instrument embodiment (184), which is showncoupled with a sheath instrument (30). Instrument (184) has a singlecontrol element interface assembly (132) and two control elements (192),with a spring-loaded idler (198) tensioning of the control elements(192), as shown in FIG. 70. As with the aforementioned spring-loadedidler tensioning instrument embodiments, the spring-loaded idlers urge(200) the control elements (192) into tension to facilitate control.

FIG. 71 illustrates a still further instrument embodiment (186), whichis shown coupled with a sheath instrument (30). Instrument (186) has asingle control element interface assembly (132) and two control elements(192), with a single-slotted guide instrument base, as shown in FIG. 72.As with the aforementioned slotted-tensioning instrument embodiments,the slot facilitates tensioning of the control elements from a mechanismin the instrument driver below. FIG. 73 depicts the embodiment of FIG.72, with both portions of the slotted guide instrument base (202)intact. Depending upon the amount of tensioning deflection within theslot (190), it may be desirable to remove the rotational range of motionlimitation pin (not shown) from the manual adjustment knob (not shown)to prevent impingement of the pin, knob, and instrument base (202), asthe control element interface assembly is moved in the slot (190)relative to the rest of the instrument base (202).

Referring to FIGS. 74-93, elements of a sheath instrument embodimentwill now be described. Again, for ease in illustration, many of the samecomponents from the previously described instrument embodiments isutilized in these further embodiments, although such component matchingis by no means required to accomplish the described functions.

FIG. 74 depicts a guide instrument (18) shown coupled coaxially with asheath instrument (30), together forming what has been described as aset of instruments (28). In FIGS. 75 and 76, the sheath instrument (30)is depicted without the guide instrument of FIG. 74. In FIG. 76, thesheath instrument (30) is depicted having one control element interfaceassembly (132), and preferably only one control element (not shown).From a functional perspective, in most embodiments the sheath instrumentneed not be as driveable or controllable as the associated guideinstrument, because the sheath instrument is generally used tocontribute to the remote tissue access schema by providing a conduit forthe guide instrument, and to point the guide in generally the rightdirection. Such movement is controlled by rolling the sheath relative tothe patient, bending the sheath in one or more directions with a controlelement, and inserting the sheath into the patient. The seal (204) isgenerally larger than the seal on the guide instrument due to the largerdiameters of elongate members that may be inserted into the sheathinstrument (30) as part of a medical procedure. Adjacent the seal (204)is an access port (206), which may be utilized to purge the instrument,or circulate fluids or instruments. The bottom (210) and top (212)portions of the sheath instrument base (48) are preferably sandwiched tohouse portions of the control element interface assembly, such as thesingle pulley in this embodiment, and the proximal portion of the sheathcatheter member (208).

Referring to FIG. 77, the bottom portion of one embodiment of a sheathinstrument base is depicted showing two magnets utilized to facilitatemounting against an instrument driver. Mounting pin interface holes(168) also assist in accurate interfacing with an instrument driver. Theopposite surface is formed with a sheath catheter member geometryaccommodation (214) to interface with the sheath catheter (not shown).FIG. 78 shows this opposite surface in further detail, having a pulleygeometry accommodation (218), a seal geometry accommodation (216), and asheath catheter geometry accommodation (214). There is also a controlelement splay track (220) similar to those depicted in reference to theembodiments of the guide instrument. In FIG. 79, a bottom view of a topportion (212) of one embodiment of a sheath instrument base (48) isdepicted showing the sheath catheter geometry (214) and seal geometry(216) accommodations formed therein, and an axel interface hole (222)formed there through.

FIG. 80 illustrates yet another embodiment of the sheath catheter (208)in a pre-bent formation, which may be desirable depending upon theanatomical issue pertinent to the medical procedure. The sheath catheter(208) preferably has a construction somewhat similar to that of theaforementioned guide catheter member embodiments, with notableexceptions. For one, it preferably does not have a flexible structuralelement disposed within its distal end, as it is not within thepreferred functionality of the sheath instrument to have very tightradius bendability, particularly given the high bendability of theassociated guide instrument. Preferably both the proximal (224) anddistal (226) portions comprise a low-friction inner layer, a braidinglayer, and an outer layer, as described below with reference to FIG. 81.It is preferable to have more bending flexibility in the distal portionthan in the proximal portion. This may be accomplished by selecting aouter layer polymeric material for the distal portion (226) havingapproximately half the durometer of the polymeric material utilized forthe outer layer of the proximal portion (224). In the depictedembodiment, an atraumatic distal tip (228) comprising an extension ofthe low-friction inner layer and outer layer extends slightly beyond thetermination of the braiding layer by between about ¼ inch and ⅛ inch toprevent damage to tissues in various medical procedures.

FIG. 81 is a cross sectional view of a proximal or distal portion of asheath catheter member (208), similar to that shown in FIG. 80. Abraiding layer (230) is surrounded by an outer layer (232) preferablycomprising a polymer such as Pebax™ with a durometer between about 30and 80, and an inner layer (234) preferably comprising a low-frictionpolymeric material into which one or more lumens may be optionallyextruded. The embodiment of FIG. 81 depicts one control element lumen(236). The geometry of the inner layer (234) may be configured to “key”or restrictively interface with a guide catheter member outer geometryto prevent rotation of the guide catheter member as discussed below withreference to FIGS. 85-91. The central lumen (238) of the sheath catheterpreferably is sized to closely fit the associated guide catheter member.FIG. 82 depicts an embodiment similar to that shown in FIG. 81, with theexception that it does not have a control element lumen. In someembodiments, it is preferable not to have a steerable sheath catheter,but instead to have a straight or pre-bent sheath catheter, or no sheathcatheter at all, surrounding a portion of the guide catheter.

Referring to FIGS. 83 and 84, an embodiment of a sheath catheter memberis depicted with an inner layer (234) configured to key with a3-control-element guide geometry, such as that depicted in FIG. 21. FIG.84 depicts a similar embodiment, without a control element lumen (236).FIG. 85 depicts an non-keyed sheath without any control element lumensto illustrate that keying and steerable control is not necessary ordesired in some embodiments or procedures—particularly when morebendability of the sheath is desired. The embodiment of FIG. 85 isrelatively thin walled, and while it still comprises a braiding layer(230) surrounded by an outer layer (232) and an inner layer (234) ofpolymeric material, it is generally more easily bendable throughtortuous paths than are other more thick-walled embodiments. Further,without the keying geometry of the inner layer (234), the central lumen(238) is effectively larger.

FIGS. 86-91 illustrate cross sectional representations of variousembodiments of coaxially coupled guide catheter (90) and sheath catheter(208) combinations.

Referring to FIG. 86, a relatively low surface profile (104) guidecatheter is disposed within sheath catheter (208) having four controlelement lumens. The fit between the two structures is fairly loose, andsome relative rotational displacement is to be expected if the guidecatheter (90) is torqued significantly more than the sheath catheter(208). To help prevent such relative rotational displacement, a higherprofile guide catheter (90) geometry may be utilized, as shown in FIG.87, in order to decrease the freedom of movement between the twostructures as they are bent through the pathways required by a medicalprocedure.

FIG. 88 depicts an embodiment similar to that in FIG. 87, but withoutthe control element lumens. It may be desirable to have control elementlumens formed into the walls of the guide catheter or sheath catheterfor reasons other than passing control elements through such lumens.These lumens may function as stress relief structures to increasebendability. They may also be utilized to form preferred bending axesfor the overall structure. Further, they may be utilized as workingchannels for flushing, drug delivery, markers, sensors, illuminationfibers, vision fibers, and the like. It may be desirable to have ahomogeneous patterning of control lumens across the cross section of aparticular structure in order to promote homogeneous bending. Forexample, a sheath catheter with four control lumens, one of which isoccupied by a control element in tension, may bend more homogeneouslythan a sheath catheter with only one or two control lumens, one of whichoccupied by a control element.

Referring to FIG. 89, a relatively high surface profile (106) guidecatheter (90) is depicted within a non-keyed sheath catheter, with a4-control-element guide catheter disposed within a pre-bent sheathinstrument that is not remotely steerable. FIG. 90 depicts a similarembodiment to that of FIG. 89, with the exception of an even lowersurface profile (104) guide catheter (90) disposed within the non-keyedsheath catheter. FIG. 91 depicts a somewhat extreme example of keying toresist relative rotational displacement between a guide catheter (90)and a sheath catheter (208). Significant resistance to rotationaldisplacement is traded for higher degrees of overall system bendability,as will be apparent to those skilled in the art. As shown in FIG. 92, apreferably elastomeric seal (204) and access port (206) construct may befitted onto the sheath catheter member (208), prior to mounting withinthe confines of the sheath instrument base (46). FIG. 93 is a side viewof the sheath catheter member (208) coupled to the seal (204) and accessport (206). FIG. 94 is an end view of the seal (204).

FIGS. 95-103 depict various aspects of embodiments of an instrumentdriver configured for use with the above-described instrumentembodiments.

FIGS. 95 and 96 are simplified schematics that illustrate internalfeatures and functionalities of one embodiment of an instrument driver.In FIG. 95, a carriage (240) is slidably mounted upon a platform (246),which is slidably mounted to a base structure (248). The slidablemounting (250) at these interfaces may be accomplished withhigh-precision linear bearings. The depicted system has two cables (256,258) running through a plurality of pulleys (244) to accomplishmotorized, synchronized relative motion of the carriage (240) andplatform (246) along the slidable interfaces (250). As will be apparentto those skilled in the art, as the motor (242) pulls on the carriagedisplacement cable (256) with a tension force T, the carriage (240)feels a force of 2*T. Further, as the motor pulls the carriagedisplacement cable (256) by a displacement X, the carriage moves by X/2,and the platform moves by half that amount, or X/4, due to its“pulleyed” synchronization cable (258).

FIG. 96 illustrates a top view of a separate (but similar) systemconfigured to drive an instrument interface pulley (260) associated withan instrument interface socket (262) to produce both directions ofrotation independently from the position of the carriage (240), to whichit is coupled, along the linear pathway prescribed by the slidableinterfaces (250). With a mechanical schema similar to that in FIG. 96,as the motor (242) pulls a deflection X in the instrument interfacecable (264), the same deflection is seen directly at the instrumentinterface pulley (260), regardless of the position of the carriage (240)relative to the motor (242), due to the synchronizing cable (266)positioning and termination (252).

Referring to FIGS. 97-103, systems similar to those depicted in FIGS. 95and 96 are incorporated into various embodiments of the instrumentdriver. In FIG. 97, an instrument driver (16) is depicted as interfacedwith a steerable guide instrument (18) and a steerable sheath instrument(30). FIG. 98 depicts an embodiment of the instrument driver (16), inwhich the sheath instrument interface surface (38) remains stationary,and requires only a simple motor actuation in order for a sheath to besteered using an interfaced control element via a control elementinterface assembly (132). This may be accomplished with a simple cableloop about a sheath socket drive pulley (272) and a capstan pulley (notshown), which is fastened to a motor, similar to the two upper motors(242) (visible in FIG. 98). The drive motor for the sheath socket driveschema is hidden under the linear bearing interface assembly.

The drive schema for the four guide instrument interface sockets (270)is more complicated, due in part to the fact that they are coupled to acarriage (240) configured to move linearly along a linear bearinginterface (250) to provide for motor-driven insertion of a guideinstrument toward the patient relative to the instrument driver,hospital table, and sheath instrument. The cabling and motor schema thatmoves the carriage (240) along the linear bearing interface (250) is animplementation of the diagrammatic view depicted in FIG. 95. The cablingand motor schema that drives each of the four depicted guide instrumentinterface sockets is an implementation of the diagrammatic view depictedin FIG. 96. Therefore, in the embodiments of FIGS. 98-103, wherein fourseparate cable drive loops serve four separate guide instrumentinterface sockets (270), and wherein the carriage (240) has motorizedinsertion, there is achieved a functional equivalent of a system such asthat diagrammed in FIGS. 95 and 96, all fit into the same construct.Various conventional cable termination and routing techniques areutilized to accomplish a preferably high-density instrument driverstructure with the carriage (240) mounted forward of the motors for alower profile patient-side interface.

Still referring to FIG. 98, the instrument driver (16) is rotatablymounted to an instrument driver base (274), which is configured tointerface with an instrument driver mounting brace (not shown), such asthat depicted in FIG. 1, or a movable setup joint construct (not shown),such as that depicted in FIG. 2. Rotation between the instrument driverbase (274) and an instrument driver base plate (276) to which it iscoupled is facilitated by a heavy-duty flanged bearing structure (278).The flanged bearing structure (278) is configured to allow rotation ofthe body of the instrument driver (16) about an axis approximatelycoincident with the longitudinal axis of a guide instrument (not shown)when the guide instrument is mounted upon the instrument driver (16) ina neutral position. This rotation preferably is automated or powered bya roll motor (280) and a simple roll cable loop (286), which extendsaround portions of the instrument driver base plate and terminates asdepicted (282, 284). Alternatively, roll rotation may be manuallyactuated and locked into place with a conventional clamping mechanism.The roll motor (280) position is more easily visible in FIG. 99.

FIG. 100 illustrates another embodiment of an instrument driver,including a group of four motors (290). Each motor (290) has anassociated high-precision encoder for controls purposes and beingconfigured to drive one of the four guide instrument interface sockets(270), at one end of the instrument driver. Another group of two motors(one hidden, one visible —288) with encoders (292) are configured todrive insertion of the carriage (240) and the sheath instrumentinterface socket (268).

Referring to FIG. 101, a further embodiment of an instrument driver isdepicted to show the position of the carriage (240) relative to thelinear bearing interfaces (250). Also shown is the interfacing of aportion of a instrument interface cable (264) as it bends around apulley (244) and completes part of its loop to an instrument interfacepulley (260) rotatably coupled to the carriage (240) and coupled to aguide instrument interface socket (270), around the instrument interfacepulley (260), and back to a motor capstan pulley (294). To facilitateadjustment and installation of such cable loops, and due to the factthat there is generally no requirement to have a loop operating for along period of time in one direction, thereby perhaps requiring a trueunterminated loop, two ends of a cut cable loop preferably areterminated at each capstan (294).

The carriage (240) depicted in the embodiments of FIGS. 97-101 generallycomprises a structural box configured to house the instrument interfacesockets and associated instrument interface pulleys. Referring to FIGS.102 and 103, a split carriage (296) is depicted, comprising a maincarriage body (304) similar to that of the non split carriage depictedin previous embodiments (240), and either one or two linearly movableportions (302), which are configured to slide relative to the maincarriage body (304) when driven along either forward or backwardrelative to the main carriage body by a gear (300) placed into one ofthe guide instrument interface sockets, the gear (300) configured tointerface with a rack (298) mounted upon the main carriage body (304)adjacent the gear (300). In an alternate embodiment, the carriage neednot be split on both sides, but may have one split side and onenon-split side. Further, while a carriage with four guide instrumentinterface sockets is suitable for driving a guide instrument withanywhere from one to four control element interface assemblies, theadditional hardware required for all four control element interfaceassemblies may be undesirable if an instrument only requires only one ortwo.

Referring to FIG. 104, an operator control station is depicted showing acontrol button console (8), a computer (6), a computer control interface(10), such as a mouse, a visual display system (4) and a master inputdevice (12). In addition to “buttons” on the button console (8)footswitches and other known user control interfaces may be utilized toprovide an operator interface with the system controls. Referring toFIG. 105A, in one embodiment, the master input device (12) is amulti-degree-of-freedom device having multiple joints and associatedencoders (306). Further, the master input device may have integratedhaptics capability for providing tactile feedback to the user. Anotherembodiment of a master input device (12) is depicted in FIG. 105B.Suitable master input devices are available from manufacturers such asSensible Devices Corporation under the trade name “Phantom™”, or ForceDimension under the trade name “Omega™”.

Referring to FIGS. 106-109, the basic kinematics of a catheter with fourcontrol elements is reviewed.

Referring to FIGS. 106 A-B, as tension is placed only upon the bottomcontrol element (312), the catheter bends downward, as shown in FIG.106A. Similarly, pulling the left control element (314) in FIGS. 107 A-Bbends the catheter left, pulling the right control element (310) inFIGS. 108 A-B bends the catheter right, and pulling the top controlelement (308) in FIGS. 109 A-B bends the catheter up. As will beapparent to those skilled in the art, well-known combinations of appliedtension about the various control elements results in a variety ofbending configurations at the tip of the catheter member (90). One ofthe challenges in accurately controlling a catheter or similar elongatemember with tension control elements is the retention of tension incontrol elements, which may not be the subject of the majority of thetension loading applied in a particular desired bending configuration.If a system or instrument is controlled with various levels of tension,then losing tension, or having a control element in a slackconfiguration, can result in an unfavorable control scenario.

Referring to FIGS. 110A-E, a simple scenario is useful in demonstratingthis notion. As shown in FIG. 110A, a simple catheter (316) steered withtwo control elements (314, 310) is depicted in a neutral position. Ifthe left control element (314) is placed into tension greater than thetension, if any, which the right control element (310) experiences, thecatheter (316) bends to the left, as shown in FIG. 110B. If a change ofdirection is desired, this paradigm needs to reverse, and the tension inthe right control element (310) needs to overcome that in the leftcontrol element (314). At the point of a reversal of direction likethis, where the tension balance changes from left to right, withoutslack or tension control, the right most control element (314) maygather slack which needs to be taken up before precise control can bereestablished. Subsequent to a “reeling in” of slack which may bepresent, the catheter (316) may be may be pulled in the oppositedirection, as depicted in FIGS. 110C-E, without another slack issue froma controls perspective until a subsequent change in direction.

The above-described instrument embodiments present various techniquesfor managing tension control in various guide instrument systems havingbetween two and four control elements. For example, in one set ofembodiments, tension may be controlled with active independenttensioning of each control element in the pertinent guide catheter viaindependent control element interface assemblies (132) associated withindependently-controlled guide instrument interface sockets (270) on theinstrument driver (16). Thus, tension may be managed by independentlyactuating each of the control element interface assemblies (132) in afour-control-element embodiment, such as that depicted in FIGS. 18 and47, a three-control-element embodiment, such as that depicted in FIGS.63 and 64, or a two-control-element embodiment, such as that depicted inFIGS. 56 and 66.

In another set of embodiments, tension may be controlled with activeindependent tensioning with a split carriage design, as described inreference to FIGS. 102 and 103. For example, with an instrumentembodiment similar to that depicted in FIGS. 53, 54, and 56, a splitcarriage with two independent linearly movable portions, such as thatdepicted in FIG. 103, may be utilized to actively and independentlytension each of the two control element interface assemblies (132), eachof which is associated with two dimensions of a given degree of freedom.For example, there can be + and −pitch on one interface assembly, + and−yaw on the other interface assembly, with slack or tension controlprovided for pitch by one of the linearly movable portions (302) of thesplit carriage (296), and slack or tension control provided for yaw bythe other linearly movable portion (302) of the split carriage (296).

Similarly, with an embodiment similar to that of FIGS. 71-73, slack ortension control for a single degree of freedom, such as yaw or pitch,may be provided by a single-sided split carriage design similar to thatof FIG. 103, with the exception that only one linearly movable portionwould be required to actively tension the single control elementinterface assembly of an instrument.

In another set of embodiments, tensioning may be controlled withspring-loaded idlers configured to keep the associated control elementsout of slack, as in the embodiments depicted in FIGS. 57-62 and 69-70.The control elements preferably are pre-tensioned in each embodiment toprevent slack and provide predictable performance. Indeed, in yetanother set of embodiments, pre-tensioning may form the main source oftension management, as in the embodiments depicted in FIGS. 55 and67-68. In the case of embodiments only having pre-tensioning orspring-loaded idler tensioning, the control system may need to beconfigured to reel in bits of slack at certain transition points incatheter bending, such as described above in relation to FIGS. 110A and110B.

To accurately coordinate and control actuations of various motors withinan instrument driver from a remote operator control station such as thatdepicted in FIG. 1, an advanced computerized control and visualizationsystem is preferred. While the control system embodiments that followare described in reference to a particular control systems interface,namely the SimuLink™ and XPC™ control interfaces available from TheMathworks Inc., and PC-based computerized hardware configurations, manyother configurations may be utilized, including various pieces ofspecialized hardware, in place of more flexible software controlsrunning on PC-based systems.

Referring to FIG. 111, an overview of an embodiment of a controls systemflow is depicted. A master computer (400) running master input devicesoftware, visualization software, instrument localization software, andsoftware to interface with operator control station buttons and/orswitches is depicted. In one embodiment, the master input devicesoftware is a proprietary module packaged with an off-the-shelf masterinput device system, such as the Phantom™ from Sensible DevicesCorporation, which is configured to communicate with the Phantom™hardware at a relatively high frequency as prescribed by themanufacturer. Other suitable master input devices, such as that (12)depicted in FIG. 105B are available from suppliers such as ForceDimension of Lausanne, Switzerland. The master input device (12) mayalso have haptics capability to facilitate feedback to the operator, andthe software modules pertinent to such functionality may also beoperated on the master computer (400). Preferred embodiments of hapticsfeedback to the operator are discussed in further detail below.

The term “localization” is used in the art in reference to systems fordetermining and/or monitoring the position of objects, such as medicalinstruments, in a reference coordinate system. In one embodiment, theinstrument localization software is a proprietary module packaged withan off-the-shelf or custom instrument position tracking system, such asthose available from Ascension Technology Corporation, Biosense Webster,Inc., Endocardial Solutions, Inc., Boston Scientific (EP Technologies),and others. Such systems may be capable of providing not only real-timeor near real-time positional information, such as X-Y-Z coordinates in aCartesian coordinate system, but also orientation information relativeto a given coordinate axis or system. Referring to FIGS. 112A and 112B,various localization sensing systems may be utilized with the variousembodiments of the robotic catheter system disclosed herein. In otherembodiments not comprising a localization system to determine theposition of various components, kinematic and/or geometric relationshipsbetween various components of the system may be utilized to predict theposition of one component relative to the position of another. Someembodiments may utilize both localization data and kinematic and/orgeometric relationships to determine the positions of variouscomponents.

As shown in FIG. 112A, one preferred localization system comprises anelectromagnetic field transmitter (406) and an electromagnetic fieldreceiver (402) positioned within the central lumen of a guide catheter(90). The transmitter (406) and receiver (402) are interfaced with acomputer operating software configured to detect the position of thedetector relative to the coordinate system of the transmitter (406) inreal or near-real time with high degrees of accuracy. Referring to FIG.112B, a similar embodiment is depicted with a receiver (404) embeddedwithin the guide catheter (90) construction. Preferred receiverstructures may comprise three or more sets of very small coils spatiallyconfigured to sense orthogonal aspects of magnetic fields emitted by atransmitter. Such coils may be embedded in a custom configuration withinor around the walls of a preferred catheter construct. For example, inone embodiment, two orthogonal coils are embedded within a thinpolymeric layer at two slightly flattened surfaces of a catheter (90)body approximately ninety degrees orthogonal to each other about thelongitudinal axis of the catheter (90) body, and a third coil isembedded in a slight polymer-encapsulated protrusion from the outside ofthe catheter (90) body, perpendicular to the other two coils. Due to thevery small size of the pertinent coils, the protrusion of the third coilmay be minimized. Electronic leads for such coils may also be embeddedin the catheter wall, down the length of the catheter body to aposition, preferably adjacent an instrument driver, where they may berouted away from the instrument to a computer running localizationsoftware and interfaced with a pertinent transmitter.

Referring back to FIG. 111, in one embodiment, visualization softwareruns on the master computer (400) to facilitate real-time driving andnavigation of one or more steerable instruments. In one embodiment,visualization software provides an operator at an operator controlstation, such as that depicted in FIG. 1 (2), with a digitized“dashboard” or “windshield” display to enhance instinctive drivabilityof the pertinent instrumentation within the pertinent tissue structures.Referring to FIG. 113, a simple illustration is useful to explain oneembodiment of a preferred relationship between visualization andnavigation with a master input device (12). In the depicted embodiment,two display views (410, 412) are shown. One preferably represents aprimary (410) navigation view, and one may represent a secondary (412)navigation view. To facilitate instinctive operation of the system, itis preferable to have the master input device coordinate system at leastapproximately synchronized with the coordinate system of at least one ofthe two views. Further, it is preferable to provide the operator withone or more secondary views which may be helpful in navigating throughchallenging tissue structure pathways and geometries.

Using the operation of an automobile as an example, if the master inputdevice is a steering wheel and the operator desires to drive a car in aforward direction using one or more views, his first priority is likelyto have a view straight out the windshield, as opposed to a view out theback window, out one of the side windows, or from a car in front of thecar that he is operating. The operator might prefer to have the forwardwindshield view as his primary display view, such that a right turn onthe steering wheel takes him right as he observes his primary display, aleft turn on the steering wheel takes him left, and so forth. If theoperator of the automobile is trying to park the car adjacent anothercar parked directly in front of him, it might be preferable to also havea view from a camera positioned, for example, upon the sidewalk aimedperpendicularly through the space between the two cars (one driven bythe operator and one parked in front of the driven car), so the operatorcan see the gap closing between his car and the car in front of him ashe parks. While the driver might not prefer to have to completelyoperate his vehicle with the sidewalk perpendicular camera view as hissole visualization for navigation purposes, this view is helpful as asecondary view.

Referring still to FIG. 113, if an operator is attempting to navigate asteerable catheter in order to, for example, contact a particular tissuelocation with the catheter's distal tip, a useful primary navigationview (410) may comprise a three dimensional digital model of thepertinent tissue structures (414) through which the operator isnavigating the catheter with the master input device (12), along with arepresentation of the catheter distal tip location (416) as viewed alongthe longitudinal axis of the catheter near the distal tip. Thisembodiment illustrates a representation of a targeted tissue structurelocation (418), which may be desired in addition to the tissue digitalmodel (414) information. A useful secondary view (412), displayed upon adifferent monitor, in a different window upon the same monitor, orwithin the same user interface window, for example, comprises anorthogonal view depicting the catheter tip representation (416), andalso perhaps a catheter body representation (420), to facilitate theoperator's driving of the catheter tip toward the desired targetedtissue location (418).

In one embodiment, subsequent to development and display of a digitalmodel of pertinent tissue structures, an operator may select one primaryand at least one secondary view to facilitate navigation of theinstrumentation. By selecting which view is a primary view, the user canautomatically toggle a master input device (12) coordinate system tosynchronize with the selected primary view. In an embodiment with theleftmost depicted view (410) selected as the primary view, to navigatetoward the targeted tissue site (418), the operator should manipulatethe master input device (12) forward, to the right, and down. The rightview will provide valued navigation information, but will not be asinstinctive from a “driving” perspective.

To illustrate: if the operator wishes to insert the catheter tip towardthe targeted tissue site (418) watching only the rightmost view (412)without the master input device (12) coordinate system synchronized withsuch view, the operator would have to remember that pushing straightahead on the master input device will make the distal tip representation(416) move to the right on the rightmost display (412). Should theoperator decide to toggle the system to use the rightmost view (412) asthe primary navigation view, the coordinate system of the master inputdevice (12) is then synchronized with that of the rightmost view (412),enabling the operator to move the catheter tip (416) closer to thedesired targeted tissue location (418) by manipulating the master inputdevice (12) down and to the right.

The synchronization of coordinate systems described herein may beconducted using fairly conventional mathematic relationships. Forexample, in one embodiment, the orientation of the distal tip of thecatheter may be measured using a 6-axis position sensor system such asthose available from Ascension Technology Corporation, Biosense Webster,Inc., Endocardial Solutions, Inc., Boston Scientific (EP Technologies),and others. A 3-axis coordinate frame, C, for locating the distal tip ofthe catheter, is constructed from this orientation information. Theorientation information is used to construct the homogeneoustransformation matrix, T_(C0) ^(G0), which transforms a vector in theCatheter coordinate frame “C” to the fixed Global coordinate frame “G”in which the sensor measurements are done (the subscript C₀ andsuperscript G₀ are used to represent the 0'th, or initial, step). As aregistration step, the computer graphics view of the catheter is rotateduntil the master input and the computer graphics view of the catheterdistal tip motion are coordinated and aligned with the camera view ofthe graphics scene. The 3-axis coordinate frame transformation matrixT_(Gref) ^(G0) for the camera position of this initial view is stored(subscripts G_(ref) and superscript C_(ref) stand for the global andcamera “reference” views). The corresponding catheter “reference view”matrix for the catheter coordinates is obtained as:T _(Gref) ^(C0) =T _(G0) ^(C0) T _(Gref) ^(G0) T _(Cref) ^(Gref)=(T_(C0) ^(G0))⁻¹ T _(Gref) ^(G0) T _(C1) ^(G1)

Also note that the catheter's coordinate frame is fixed in the globalreference frame G, thus the transformation matrix between the globalframe and the catheter frame is the same in all views, i.e., T_(C0)^(G0)=T_(Cref) ^(Gref)=T_(Ci) ^(Gi) for any arbitrary view i.

The coordination between primary view and master input device coordinatesystems is achieved by transforming the master input as follows: Givenany arbitrary computer graphics view of the representation, e.g. thei'th view, the 3-axis coordinate frame transformation matrix T_(Gi)^(G0) of the camera view of the computer graphics scene is obtained formthe computer graphics software. The corresponding cathetertransformation matrix is computed in a similar manner as above:T _(Ci) ^(C0) =T _(G0) ^(C0) T _(Gi) ^(G0) T _(Ci) ^(Gi)=(T _(C0)^(G0))⁻¹ T _(Gi) ^(G0) T _(Ci) ^(Gi)The transformation that needs to be applied to the master input whichachieves the view coordination is the one that transforms from thereference view that was registered above, to the current ith view, i.e.,T_(Cref) ^(Ci). Using the previously computed quantities above, thistransform is computed as:T _(Cref) ^(Ci) =T _(C0) ^(Ci) T _(Cref) ^(C0)The master input is transformed into the commanded catheter input byapplication of the transformation T_(Cref) ^(Ci). Given a command input

${r_{master} = \begin{bmatrix}x_{master} \\y_{master} \\y_{master}\end{bmatrix}},$one may calculate:

$r_{catheter} = {\begin{bmatrix}x_{catheter} \\y_{catheter} \\y_{catheter}\end{bmatrix} = {{T_{Cref}^{Ci}\begin{bmatrix}x_{master} \\y_{master} \\y_{master}\end{bmatrix}}.}}$Under such relationships, coordinate systems of the primary view andmaster input device may be aligned for instinctive operation.

Referring back to embodiment of FIG. 111, the master computer (400) alsocomprises software and hardware interfaces to operator control stationbuttons, switches, and other input devices which may be utilized, forexample, to “freeze” the system by functionally disengaging the masterinput device as a controls input, or provide toggling between variousscaling ratios desired by the operator for manipulated inputs at themaster input device (12). The master computer (400) has two separatefunctional connections with the control and instrument driver computer(422): one (426) for passing controls and visualization relatedcommands, such as desired XYZ) in the catheter coordinate system)commands, and one (428) for passing safety signal commands. Similarly,the control and instrument driver computer (422) has two separatefunctional connections with the instrument and instrument driverhardware (424): one (430) for passing control and visualization relatedcommands such as required-torque-related voltages to the amplifiers todrive the motors and encoders, and one (432) for passing safety signalcommands.

In one embodiment, the safety signal commands represent a simple signalrepeated at very short intervals, such as every 10 milliseconds, suchsignal chain being logically read as “system is ok, amplifiers stayactive”. If there is any interruption in the safety signal chain, theamplifiers are logically toggled to inactive status and the instrumentcannot be moved by the control system until the safety signal chain isrestored. Also shown in the signal flow overview of FIG. 111 is apathway (434) between the physical instrument and instrument driverhardware back to the master computer to depict a closed loop systemembodiment wherein instrument localization technology, such as thatdescribed in reference to FIGS. 112A-B, is utilized to determine theactual position of the instrument to minimize navigation and controlerror, as described in further detail below.

FIGS. 114-124 depict various aspects of one embodiment of a SimuLink™software control schema for an embodiment of the physical system, withparticular attention to an embodiment of a “master following mode.” Inthis embodiment, an instrument is driven by following instructions froma master input device, and a motor servo loop embodiment, whichcomprises key operational functionality for executing upon commandsdelivered from the master following mode to actuate the instrument.

FIG. 114 depicts a high-level view of an embodiment wherein any one ofthree modes may be toggled to operate the primary servo loop (436). Inidle mode (438), the default mode when the system is started up, all ofthe motors are commanded via the motor servo loop (436) to servo abouttheir current positions, their positions being monitored with digitalencoders associated with the motors. In other words, idle mode (438)deactivates the motors, while the remaining system stays active. Thus,when the operator leaves idle mode, the system knows the position of therelative components. In auto home mode (440), cable loops within anassociated instrument driver, such as that depicted in FIG. 97, arecentered within their cable loop range to ensure substantiallyequivalent range of motion of an associated instrument, such as thatdepicted in FIG. 17, in both directions for a various degree of freedom,such as + and − directions of pitch or yaw, when loaded upon theinstrument driver. This is a setup mode for preparing an instrumentdriver before an instrument is engaged.

In master following mode (442), the control system receives signals fromthe master input device, and in a closed loop embodiment from both amaster input device and a localization system, and forwards drivesignals to the primary servo loop (436) to actuate the instrument inaccordance with the forwarded commands. Aspects of this embodiment ofthe master following mode (442) are depicted in further detail in FIGS.119-124. Aspects of the primary servo loop and motor servo block (444)are depicted in further detail in FIGS. 115-118.

Referring to FIG. 119, a more detailed functional diagram of anembodiment of master following mode (442) is depicted. As shown in FIG.119, the inputs to functional block (446) are XYZ position of the masterinput device in the coordinate system of the master input device which,per a setting in the software of the master input device may be alignedto have the same coordinate system as the catheter, and localization XYZposition of the distal tip of the instrument as measured by thelocalization system in the same coordinate system as the master inputdevice and catheter. Referring to FIG. 120 for a more detailed view offunctional block (446) of FIG. 119, a switch (460) is provided at blockto allow switching between master inputs for desired catheter position,to an input interface (462) through which an operator may command thatthe instrument go to a particular XYZ location in space. Variouscontrols features may also utilize this interface to provide an operatorwith, for example, a menu of destinations to which the system shouldautomatically drive an instrument, etc. Also depicted in FIG. 120 is amaster scaling functional block (464) which is utilized to scale theinputs coming from the master input device with a ratio selectable bythe operator. The command switch (460) functionality includes a low passfilter to weight commands switching between the master input device andthe input interface (462), to ensure a smooth transition between thesemodes.

Referring back to FIG. 119, desired position data in XYZ terms is passedto the inverse kinematics block (450) for conversion to pitch, yaw, andextension (or “insertion”) terms in accordance with the predictedmechanics of materials relationships inherent in the mechanical designof the instrument.

The kinematic relationships for many catheter instrument embodiments maybe modeled by applying conventional mechanics relationships. In summary,a control-element-steered catheter instrument is controlled through aset of actuated inputs. In a four-control-element catheter instrument,for example, there are two degrees of motion actuation, pitch and yaw,which both have + and − directions. Other motorized tensionrelationships may drive other instruments, active tensioning, orinsertion or roll of the catheter instrument. The relationship betweenactuated inputs and the catheter's end point position as a function ofthe actuated inputs is referred to as the “kinematics” of the catheter.

Referring to FIG. 125, the “forward kinematics” expresses the catheter'send-point position as a function of the actuated inputs while the“inverse kinematics” expresses the actuated inputs as a function of thedesired end-point position. Accurate mathematical models of the forwardand inverse kinematics are essential for the control of a roboticallycontrolled catheter system. For clarity, the kinematics equations arefurther refined to separate out common elements, as shown in FIG. 125.The basic kinematics describes the relationship between the taskcoordinates and the joint coordinates. In such case, the taskcoordinates refer to the position of the catheter end-point while thejoint coordinates refer to the bending (pitch and yaw, for example) andlength of the active catheter. The actuator kinematics describes therelationship between the actuation coordinates and the jointcoordinates. The task, joint, and bending actuation coordinates for therobotic catheter are illustrated in FIG. 126. By describing thekinematics in this way we can separate out the kinematics associatedwith the catheter structure, namely the basic kinematics, from thoseassociated with the actuation methodology.

The development of the catheter's kinematics model is derived using afew essential assumptions. Included are assumptions that the catheterstructure is approximated as a simple beam in bending from a mechanicsperspective, and that control elements, such as thin tension wires,remain at a fixed distance from the neutral axis and thus impart auniform moment along the length of the catheter.

In addition to the above assumptions, the geometry and variables shownin FIG. 127 are used in the derivation of the forward and inversekinematics. The basic forward kinematics, relating the catheter taskcoordinates (X_(c), Y_(c), Z_(c)) to the joint coordinates (φ_(pitch),φ_(pitch), L), is given as follows:

$\left. {X_{c} = {wc}} \right\rbrack\left\lbrack {{{{os}(\theta)}Y_{c}} = {{R\;{\sin(\alpha)}Z_{c}} = {{w\;{\sin(\theta)}{where}w} = {{{R\left( {1 - {\cos(\alpha)}} \right)}\alpha} = {{\left\lbrack {\left( \phi_{pitch} \right)^{2} + \left( \phi_{yaw} \right)^{2}} \right\rbrack^{1/2}\mspace{14mu}\left( {{total}\mspace{20mu}{bending}} \right)R} = {{\frac{L}{\alpha}\mspace{14mu}\left( {{bend}\mspace{20mu}{radius}} \right)\theta} = {{atan}\; 2\left( {\phi_{pitch},\phi_{yaw}} \right)\mspace{20mu}\left( {{roll}\mspace{20mu}{angle}} \right)}}}}}}} \right.$

The actuator forward kinematics, relating the joint coordinates(φ_(pitch), φ_(pitch), L) to the actuator coordinates (ΔL_(x), ΔL_(z),L) is given as follows:

$\phi_{pitch} = \frac{2\Delta\; L_{z}}{D_{c}}$$\phi_{yaw} = \frac{2\Delta\; L_{x}}{D_{c}}$

As illustrated in FIG. 125, the catheter's end-point position can bepredicted given the joint or actuation coordinates by using the forwardkinematics equations described above.

Calculation of the catheter's actuated inputs as a function of end-pointposition, referred to as the inverse kinematics, can be performednumerically, using a nonlinear equation solver such as Newton-Raphson. Amore desirable approach, and the one used in this illustrativeembodiment, is to develop a closed-form solution which can be used tocalculate the required actuated inputs directly from the desiredend-point positions.

As with the forward kinematics, we separate the inverse kinematics intothe basic inverse kinematics, which relates joint coordinates to thetask coordinates, and the actuation inverse kinematics, which relatesthe actuation coordinates to the joint coordinates. The basic inversekinematics, relating the joint coordinates (φ_(pitch), φ_(pitch), L), tothe catheter task coordinates (Xc, Yc, Zc) is given as follows:

ϕ_(pitch) = α sin (θ) ϕ_(yaw) = α cos (θ) L = R α $\begin{matrix}\; & {\theta = {{atan}\; 2\left( {Z_{c},X_{c}} \right)}} & \; & {\beta = {{atan}\; 2\left( {Y_{c},W_{c}} \right)}} \\\left. \rightarrow\mspace{14mu}\left. {where}\rightarrow\mspace{14mu}\rightarrow \right. \right. & {R = \frac{l\;\sin\;\beta}{\sin\; 2\;\beta}} & \rightarrow & {W_{c} = \left( {X_{c}^{2} + Z_{c}^{2}} \right)^{\frac{1}{2}}} \\\; & {\alpha = {\pi - {2\;\beta}}} & \; & {l = \left( {W_{c}^{2} + Y_{c}^{2}} \right)^{\frac{1}{2}}}\end{matrix}$

The actuator inverse kinematics, relating the actuator coordinates(ΔL_(x), ΔL_(z), L) to the joint coordinates (φ_(pitch), φ_(pitch), L)is given as follows:

${\Delta\; L_{x}} = \frac{D_{c}\phi_{yaw}}{2}$${\Delta\; L_{z}} = \frac{D_{c}\phi_{pitch}}{2}$

Referring back to FIG. 119, pitch, yaw, and extension commands arepassed from the inverse kinematics (450) to a position control block(448) along with measured localization data. FIG. 124 provides a moredetailed view of the position control block (448). After measured XYZposition data comes in from the localization system, it goes through ainverse kinematics block (464) to calculate the pitch, yaw, andextension the instrument needs to have in order to travel to where itneeds to be. Comparing (466) these values with filtered desired pitch,yaw, and extension data from the master input device, integralcompensation is then conducted with limits on pitch and yaw to integrateaway the error. In this embodiment, the extension variable does not havethe same limits (468), as do pitch and yaw (470). As will be apparent tothose skilled in the art, having an integrator in a negative feedbackloop forces the error to zero. Desired pitch, yaw, and extensioncommands are next passed through a catheter workspace limitation (452),which may be a function of the experimentally determined physical limitsof the instrument beyond which componentry may fail, deform undesirably,or perform unpredictably or undesirably. This workspace limitationessentially defines a volume similar to a cardioid-shaped volume aboutthe distal end of the instrument. Desired pitch, yaw, and extensioncommands, limited by the workspace limitation block, are then passed toa catheter roll correction block (454).

This functional block is depicted in further detail in FIG. 121, andessentially comprises a rotation matrix for transforming the pitch, yaw,and extension commands about the longitudinal, or “roll”, axis of theinstrument—to calibrate the control system for rotational deflection atthe distal tip of the catheter that may change the control elementsteering dynamics. For example, if a catheter has no rotationaldeflection, pulling on a control element located directly up at twelveo'clock should urge the distal tip of the instrument upward. If,however, the distal tip of the catheter has been rotationally deflectedby, say, ninety degrees clockwise, to get an upward response from thecatheter, it may be necessary to tension the control element that wasoriginally positioned at a nine o'clock position. The catheter rollcorrection schema depicted in FIG. 121 provides a means for using arotation matrix to make such a transformation, subject to a rollcorrection angle, such as the ninety degrees in the above example, whichis input, passed through a low pass filter, turned to radians, and putthrough rotation matrix calculations.

In one embodiment, the roll correction angle is determined throughexperimental experience with a particular instrument and path ofnavigation. In another embodiment, the roll correction angle may bedetermined experimentally in-situ using the accurate orientation dataavailable from the preferred localization systems. In other words, withsuch an embodiment, a command to, for example, bend straight up can beexecuted, and a localization system can be utilized to determine atwhich angle the defection actually went—to simply determine the in-situroll correction angle.

Referring briefly back to FIG. 119, roll corrected pitch and yawcommands, as well as unaffected extension commands, are output from theroll correction block (454) and may optionally be passed to aconventional velocity limitation block (456). Referring to FIG. 122,pitch and yaw commands are converted from radians to degrees, andautomatically controlled roll may enter the controls picture to completethe current desired position (472) from the last servo cycle. Velocityis calculated by comparing the desired position from the previous servocycle, as calculated with a conventional memory block (476) calculation,with that of the incoming commanded cycle. A conventional saturationblock (474) keeps the calculated velocity within specified values, andthe velocity-limited command (478) is converted back to radians andpassed to a tension control block (458).

Tension within control elements may be managed depending upon theparticular instrument embodiment, as described above in reference to thevarious instrument embodiments and tension control mechanisms. As anexample, FIG. 123 depicts a pre-tensioning block (480) with which agiven control element tension is ramped to a present value. Anadjustment is then added to the original pre-tensioning based upon apreferably experimentally-tuned matrix pertinent to variables, such asthe failure limits of the instrument construct and the incomingvelocity-limited pitch, yaw, extension, and roll commands. This adjustedvalue is then added (482) to the original signal for output, via gearratio adjustment, to calculate desired motor rotation commands for thevarious motors involved with the instrument movement. In thisembodiment, extension, roll, and sheath instrument actuation (484) haveno pre-tensioning algorithms associated with their control. The outputis then complete from the master following mode functionality, and thisoutput is passed to the primary servo loop (436).

Referring back to FIG. 114, incoming desired motor rotation commandsfrom either the master following mode (442), auto home mode (440), oridle mode (438) in the depicted embodiment are fed into a motor servoblock (444), which is depicted in greater detail in FIGS. 115-118.

Referring to FIG. 115, incoming measured motor rotation data fromdigital encoders and incoming desired motor rotation commands arefiltered using conventional quantization noise filtration at frequenciesselected for each of the incoming data streams to reduce noise while notadding undue delays which may affect the stability of the controlsystem. As shown in FIGS. 117 and 118, conventional quantizationfiltration is utilized on the measured motor rotation signals at about200 hertz in this embodiment, and on the desired motor rotation commandat about 15 hertz. The difference (488) between the quantizationfiltered values forms the position error which may be passed through alead filter, the functional equivalent of a proportional derivative(“PD”)+low pass filter. In another embodiment, conventional PID,lead/lag, or state space representation filter may be utilized. The leadfilter of the depicted embodiment is shown in further detail in FIG.116.

In particular, the lead filter embodiment in FIG. 116 comprises avariety of constants selected to tune the system to achieve desiredperformance. The depicted filter addresses the needs of one embodimentof a 4-control element guide catheter instrument with independentcontrol of each of four control element interface assemblies for+/−pitch and +/−yaw, and separate roll and extension control. Asdemonstrated in the depicted embodiment, insertion and roll havedifferent inertia and dynamics as opposed to pitch and yaw controls, andthe constants selected to tune them is different. The filter constantsmay be theoretically calculated using conventional techniques and tunedby experimental techniques, or wholly determined by experimentaltechniques, such as setting the constants to give a sixty degree or morephase margin for stability and speed of response, a conventional phasemargin value for medical control systems.

In an embodiment where a tuned master following mode is paired with atuned primary servo loop, an instrument and instrument driver, such asthose described above, may be “driven” accurately in three-dimensionswith a remotely located master input device. Other preferred embodimentsincorporate related functionalities, such as haptic feedback to theoperator, active tensioning with a split carriage instrument driver,navigation utilizing direct visualization and/or tissue models acquiredin-situ and tissue contact sensing, and enhanced navigation logic.

Referring to FIG. 128, in one embodiment, the master input device may bea haptic master input device, such as those available from SensibleDevices, Inc., under the trade name Phantom™, and the hardware andsoftware required for operating such a device may at least partiallyreside on the master computer. The master XYZ positions measured fromthe master joint rotations and forward kinematics are generally passedto the master computer via a parallel port or similar link and maysubsequently be passed to a control and instrument driver computer. Withsuch an embodiment, an internal servo loop for the Phantom™ generallyruns at a much higher frequency in the range of 1,000 Hz, or greater, toaccurately create forces and torques at the joints of the master.

Referring to FIG. 129, a sample flowchart of a series of operationsleading from a position vector applied at the master input device to ahaptic signal applied back at the operator is depicted. A vector (344)associated with a master input device move by an operator may betransformed into an instrument coordinate system, and in particular to acatheter instrument tip coordinate system, using a simple matrixtransformation (345). The transformed vector (346) may then be scaled(347) per the preferences of the operator, to produce ascaled-transformed vector (348). The scaled-transformed vector (348) maybe sent to both the control and instrument driver computer (422)preferably via a serial wired connection, and to the master computer fora catheter workspace check (349) and any associated vector modification(350). this is followed by a feedback constant multiplication (351)chosen to produce preferred levels of feedback, such as force, in orderto produce a desired force vector (352), and an inverse transform (353)back to the master input device coordinate system for associated hapticsignaling to the operator in that coordinate system (354).

A conventional Jacobian may be utilized to convert a desired forcevector (352) to torques desirably applied at the various motorscomprising the master input device, to give the operator a desiredsignal pattern at the master input device. Given this embodiment of asuitable signal and execution pathway, feedback to the operator in theform of haptics, or touch sensations, may be utilized in various ways toprovide added safety and instinctiveness to the navigation features ofthe system, as discussed in further detail below.

FIG. 130 is a system block diagram including haptics capability. Asshown in summary form in FIG. 130, encoder positions on the master inputdevice, changing in response to motion at the master input device, aremeasured (355), sent through forward kinematics calculations (356)pertinent to the master input device to get XYZ spatial positions of thedevice in the master input device coordinate system (357), thentransformed (358) to switch into the catheter coordinate system and(perhaps) transform for visualization orientation and preferred controlsorientation, to facilitate “instinctive driving.”

The transformed desired instrument position (359) may then be sent downone or more controls pathways to, for example, provide haptic feedback(360) regarding workspace boundaries or navigation issues, and provide acatheter instrument position control loop (361) with requisite catheterdesired position values, as transformed utilizing inverse kinematicsrelationships for the particular instrument (362) into yaw, pitch, andextension, or “insertion”, terms (363) pertinent to operating theparticular catheter instrument with open or closed loop control.

Referring to FIGS. 131-136, relationships pertinent to tension controlvia a split carriage design such as that depicted in FIGS. 102-103 aredepicted to illustrate that such a design may isolate tension controlfrom actuation for each associated degree of freedom, such as pitch oryaw of a steerable catheter instrument.

Referring to FIG. 131, some of the structures associated with a splitcarriage design, such as the embodiments depicted in FIGS. 102 and 103,include a linearly movable portion (302), a guide instrument interfacesocket (270), a gear (300), and a rack (298). Applying conventionalgeometric relationships to the physical state of the structures relatedin FIG. 131, the equations (364, 365) of FIG. 132 may be generated.Utilizing forward kinematics of the instrument, such as those describedabove in reference to a pure cantilever bending model for a catheterinstrument, the relationships of FIG. 133 may be developed for theamount of bending as a function of cable pull and catheter diameter(“Dc”) (366), and for tension (367), defined as the total amount ofcommon pull in the control elements. Combining the equations of FIGS.132 and 133, one arrives at the relationships (368, 369) depicted inFIG. 134, wherein desired actuation and desired tensioning are decoupledby the mechanics of the involved structures. Desired actuation (368) ofthe guide instrument interface socket (270) depicted in FIG. 131 is afunction of the socket's angular rotational position. Desired tensioning(369) of the associated control elements is a function of the positionof the tensioning gear (300) versus the rack (298).

Referring to FIG. 135, with a single degree of freedom actuated, such as+/−pitch or +/−yaw, and active tensioning via a split carriagemechanism, desired tension is linearly related to the absolute value ofthe amount of bending, as one would predict per the discussion above inreference to FIGS. 110A-E. The prescribed system never goes intoslack—desired tension is always positive, as shown in FIG. 135.Referring to FIG. 136, a similar relationship applies for a two degreeof freedom system with active tensioning—such as a four-cable systemwith +/−pitch and +/−yaw as the active degrees of freedom and activetensioning via a split carriage design. Since there are two dimensions,coupling terms (370) are incorporated to handle heuristic adjustmentsto, for example, minimize control element slacking and total instrumentcompression.

As discussed in reference to FIG. 113, in one embodiment, a tissuestructure model (414) may be utilized to enhance navigation. It isparticularly desirable to utilize actual data, acquired in situ, fromthe patient onto which a procedure is to be conducted, due to anatomicvariation among the patient population which may be significant,depending generally upon the subject tissue structures. For example, thegeometry of the left atrium of the human heart varies significantly frompatient to patient, according to published reports and experimentalverification in animals.

In one embodiment, focused magnetic resonance imaging, gated for heartcycle motion, and preferably gated for respiratory cycle motion, may beutilized along with conventional image cropping and thresholdingtechniques to produce a three dimensional tissue structure model. One ofthe challenges with such an imaging modality as applied to modelingactive tissue structures such as those of the heart is the gating. Inone embodiment, the gating comprises waiting for cardiac resting periodsduring diastole which are also correlated to substantially limitedrespiratory-induced motion. Acquiring a three-dimensional image of aleft atrium, for example, utilizing gated magnetic resonance, mayrequire an unacceptable amount of acquisition time, not to mention thegenerally large and expensive instrumentation required to accomplish theacquisition and fusion into a usable tissue structure model. Such amodality, however, may be preferred where cardiac and/or respiratorycyclic motion is negligible, and wherein an image or series of imagesmay be acquired and synthesized into a usable tissue structure modelcomparatively quickly.

Referring to FIGS. 137-139 a technique is depicted through which atissue structure model may be synthesized given appropriate hardware,such as an ultrasound transducer mounted upon a catheter or similarstructure, and a localization system mounted upon the same structure toenable the capture of not only ultrasound slice data, but also theposition and orientation of the transducer at the time of each sliceacquisition. In other embodiments, a similar robotic system does notinclude a localization system, in which case kinematic and/or geometricrelationships may be used to predict the location of the imaging device.

FIG. 137 depicts a human heart with a side-firing ultrasound catheter,such as those available under the trade name AcuNav™ by Siemens AG,entering the left atrium via the inferior vena cava blood vessel.Coupled to the ultrasound catheter, at or near the location of theultrasound transducer, is a localization device, such as a set oforthogonally oriented electromagnetic receiving coils, to determine theposition and orientation of the ultrasound transducer at each acquired“slice” of acquired reflected data. FIG. 138 is a view along thelongitudinal axis of the distal end of the ultrasound catheterillustrating that, by rotating the ultrasound catheter, multiple slices(500) of reflected ultrasound image data, comprising multiple structuraltissue mass location points, may be acquired, along with the positionand orientation of the ultrasound transducer for each slice of reflectedultrasound data. With such an embodiment and a targeted tissue structurethat is cyclically mobile, such the heart, each of the slices preferablyis acquired during the resting period of diastole to preventmotion-based image distortion.

In post-acquisition processing, the acquired image slice data andassociated position and orientation data may be utilized to construct athree-dimensional tissue structure model, such as that represented bythe series of slices in FIG. 139. As will be apparent to those skilledin the art, to achieve a finer “mesh” of points for image formation,more slices may be acquired and assembled as shown in FIG. 139.Utilizing conventional image thresholding techniques available, forexample, on most ultrasound mainframe devices, such as that sold underthe trade name Sequoia™ by Siemens AG, points of transition betweenblood or other fluid-filled cavity and tissue mass may be clearlyresolved to establish transition points such as those depicted in FIG.138.

Referring to FIGS. 140-148, various aspects of another embodiment foracquiring a compiling a tissue structure image is depicted. Referring toFIG. 140, applying similar principles as applied in reference to theembodiment of FIGS. 137-139, a perimetrically-firing ultrasound imageacquisition device, such as that sold under the trade name UltraICE™ byBoston Scientific Corporation, may be utilized in concert with alocalization system to acquire a series of perimetric slices (502) andassociated position and orientation data for the transducer (504) toassemble a series of tissue-cavity threshold points (506) related inspace, as depicted in FIG. 141. As illustrated in FIG. 140, a series ofrelated slices (502) is gathered as the transducer is inserted,retrieved, or both, through a cavity. As with the embodiment above, inthe case of mobile heart tissue, each of the slices preferably isacquired during the resting period of diastole to prevent motion-basedimage distortion. Further, a finer resolution tissue structure image maybe created with higher density image acquisition as the transducer isrepositioned within the targeted cavity, as will be apparent to thoseskilled in the art.

Referring to FIG. 142, a close-up isometric view of acircumferentially-firing ultrasound catheter device (508) comprising alocalization device (509) and an ultrasound transducer (510) is depictedwithin a tissue cavity acquiring a slice of data with an illustrativemeasured point at a detected density threshold at the transition betweenempty cavity and tissue wall. FIG. 143 depicts two views down thelongitudinal axis of such a catheter system to depict acquisition of aseries of density transition points about the catheter which form aslice which may be compiled into a larger three-dimensional image of thesubject cavity. Referring to FIG. 144, the conventional transformationmathematics which may be utilized to transform position and orientationdata within the acquiring catheter tip frame of reference to the groundframe of reference, or some other desired frame of reference. Indepicted mathematics for transforming position and orientation data froma local reference to a desired frame of reference of FIG. 144, the⁰P_(ij) refers to a measured point expressed in ground (or common)reference system; the ^(ij)P_(ij) refers to a measured point expressedsensor coordinate system (slice i, data point j); the

${\,_{ij}^{0}T} = \begin{bmatrix}{\,_{ij}^{0}R} & {{}_{\;}^{}{}_{{ij}{origin}}^{\;}} \\{0\mspace{14mu} 0\mspace{14mu} 0} & 1\end{bmatrix}$refers to a homogeneous transform for device coordinate system ij toglobal (or common) coordinate system 0; the ⁰ _(ij)R refers to arotation matrix with takes a vector in coordinate system ij andexpresses it in coordinate system 0; and ⁰P_(ij origin) refers to avector from origin of the ground coordinate system to the origin of thelocal device coordinate system ij, expressed in the ground coordinatesystem. FIGS. 145A and 145B depict two different views of a catheter(512) inserting straight through a tissue cavity (513) and acquiring aseries of data slices (514) along the way.

FIGS. 146A-D depict respective variations for imaging a given tissuestructure geometry with the subject embodiment. In the embodimentdepicted in FIG. 146A, a circumferentially-firing ultrasound catheter(515) is inserted straight through a cavity without regard to incomingslice data. In FIG. 146B, a variation is depicted wherein the catheterstructure carrying the ultrasound transducer and localization device isbent as it moves through the subject tissue cavity to provide a seriesof slices occupying substantially parallel planes. FIG. 146C depicts avariation wherein the catheter structure carrying the ultrasoundtransducer and localization device is directed into specificsub-portions of the subject tissue mass. In one embodiment, suchdirecting may be the result of real-time or near-real-time imageanalysis by the operator. For example, fluoroscopy or other conventionalimaging techniques may be utilized to position the catheter into such alocation in one embodiment. In another embodiment, the catheter may beautomatically or semi-automatically guided to such as position, asdiscussed below. As shown in FIG. 146D, the catheter may be inserted andsteered through the subject tissue cavity such that the planes of theslices of data acquired are not parallel. Given the known position andorientation of the ultrasound transducer from an associated localizationsystem, it is by no means a requirement that the planes within a givenimage stack be parallel. Indeed, in some embodiments, it may bedesirable to controllably bend an imaging catheter (516) near a locationof interest to acquire multiple images (517) of a particular portion ofthe subject tissue, as depicted in FIG. 147. Such controlled bendingthrough a preset range of motion as additional image slices are acquiredmay be termed “bend detailing” a particular portion of the subjecttissue structures.

Referring to FIGS. 148A-C, several acquisition protocol embodiments aredepicted for implementing the aforementioned acquisition systemembodiment. In a simple embodiment (148A), an insertion vector isselected, subsequent to which an ultrasound transducer is insertedacross a subject tissue cavity, pausing to acquire slice andposition/orientation data along the way, leading to the combination ofslice and location/orientation data into a three-dimensional model. Inanother embodiment (148B), rather than following a pre-determinedprogram for inserting across the subject cavity and acquiring dataslices, a closed-loop system analyzes incoming slice data and appliespreprogrammed logic to automatically navigate as the image acquisitioncontinues. FIG. 148C depicts an embodiment similar to that of FIG. 148B,with the exception that logical path planning is integrated into thecontrols logic operating the catheter instrument driver to provideautomated or semi-automated image acquisition functionality. Forexample, the system may watch acquired images time-of-flight betweenemitted radiation and detected reflection of such radiation to steer theinstrument directly down the middle of the cavity, as interpretedutilizing the time-of-flight data. This may be referred to as“time-of-flight center drive”. In another embodiment, significantchanges in time-of-flight data for a given sector of an image seriesover a given period of time or distance may be interpreted as a changein tissue surface geometry worth higher density localized imaging, oreven an automatic bending to take the transducer closer to the site ofinterest—or to rotate the transducer for higher-resolution imaging ofthe particular area without insertion adjustment, as described above inreference to FIG. 147.

FIGS. 149 and 150 depict respective embodiments for acquiring athree-dimensional tissue structure model of a human left atrium.

Referring to FIG. 149, subsequent to crossing the septal wall,confirming an acquisition start position adjacent the septum, andmeasuring the approximate trajectory and insertion length to reach theleft superior pulmonary vein funnel into the left atrium with theinstrument utilizing a conventional technology such as fluoroscopy orultrasound, the instrument may be driven across the left atrium cavityalong the approximate trajectory, gathering slices along the way andnoting, via time of flight calculations and anatomy logic, approximatepositioning of any other pulmonary vein funnel neckdown positions. Asthe instrument reaches the end of the predicted trajectory to the leftinferior pulmonary vein funnel, neckdown into the funnel may be detectedusing time of flight calculations and added data from bend-detailing, asdescribed above in reference to FIG. 147. After the neckdown isdetected, the instrument may be driven into the funnel and funnel shapeand trajectory data acquired for the left superior pulmonary veinstructure. In one embodiment, a preset insertion limit preventsinsertion beyond a set value into a pulmonary vein funnel structure. Inanother embodiment (such as that described in reference to FIG. 150), atissue contact sensing means may be utilized to provide feedback to anoperator or automated drive system that a tissue structure has beenphysically encountered by the instrument, and that the instrumentinsertion should be limited, as directed by the pertinent controlslogic.

Referring still to FIG. 149, subsequent to acquiring funnel shape andtrajectory data for a first pulmonary vein funnel of the left atrium, asimilar procedure may be utilized to do the same for second, third, andfourth pulmonary vein funnels. After driving back out of the leftsuperior pulmonary vein funnel, preferably along the trajectory utilizedto minimally invasively enter the funnel, the neckdown into the leftinferior pulmonary vein funnel is detected utilizing similar techniques,such as bend-detailing, and funnel and trajectory data pertinent to theleft inferior pulmonary vein is acquired. Subsequently, the instrumentmay be driven back to the location of the right pulmonary veinneckdowns, preferably starting with the more easily accessed, in mostpatients, right inferior pulmonary vein neckdown. To increase the amountand variation of data comprising the ultimate left atrium model, dataslices may be continually gathered as the instrument is driven back,forth, and around the left atrium.

After locating the right inferior pulmonary vein funnel, the instrumentmay be driven into the funnel and data acquired for the trajectory andshape, as discussed above in reference to the left pulmonary veinfunnels. Similar, shape and trajectory data may be acquired for theright superior pulmonary vein funnel, which in most patients, is themost difficult to access due to its location relative to the septum.Should bend-detailing or acquisition of slices and time of flightanalysis as facilitated by driving the instrument around within theatrium be ineffective in location any of the pulmonary vein neck downlocations, conventional systems, such as fluoroscopy or intracardiacultrasound, may be utilized during the depicted acquisition procedure toassist in generally driving the instrument to the location of thepertinent tissue structures, after which the appropriate portion of thedepicted procedure may be resumed in a more automated fashion.

Referring to FIG. 150, another embodiment of a procedure for acquiring athree-dimensional image of a left atrium is depicted, this embodimentdiffering from that of FIG. 149 in that the pertinent system alsoincorporates a contact sensing means at the distal tip of the instrumentfor sensing contact between the instrument tip and the subject tissuestructures. With such added functionality and logic to incorporate theinformation from it, the subject system may be configured to stop orindicate to the operator that a tissue structure or wall has beenengaged. Such a feature may be utilized to streamline the acquisitionprocess. For example, rather than planning a trajectory based upon datafrom imaging modalities such as fluoroscopy or ultrasound, theinstrument merely may be pointed in roughly the appropriate directionacross the left atrium toward the left pulmonary veins, and insertiondriving and data slice acquisition engaged. The contact sensing feedbackmay be logically utilized to stop insertion of the instrument at or nearthe left wall of the left atrium, or within the bends of the pulmonaryveins as they narrow away from the funnels of the left atrium.

A number of references have reported methods for determining contactbetween medical device instrumentation and tissue. For example, U.S.Pat. Nos. 5,935,079; 5,891,095; 5,836,990; 5,836,874; 5,673,704;5,662,108; 5,469,857; 5,447,529; 5,341,807; 5,078,714; and CanadianPatent Application 2,285,342 disclose various aspects of determiningelectrode-tissue contact by measuring changes in impedance between aninstrument electrode and a reference electrode. In an embodiment of thesubject invention wherein the instrument comprises suitably positionedelectrodes, techniques such as those disclosed in the art may beutilized. Other preferred embodiments of contact sensing means aredescribed in reference to FIGS. 151-157.

Referring to FIG. 151, an instrument (518) operated by an instrumentdriver and a closed-loop control system incorporating a localizationtechnology to measure actual instrument position is depicted. When theinstrument tip is driven through a range of motion, such as +pitch to−pitch, then back to neutral and +yaw to −yaw, at some cyclic interval,loads encountered by tissue structure contact, as opposed to free cavityspace in blood, for example, will tend to increase the error detectedbetween the measured tip position determined by the localization system,and the predicted tip location, determined via the inverse kinematics ofthe instrument structure. Other cyclic patterns of motion may also beutilized, such as repeated spiral motion, circular motion, etc.Depending upon the experimentally determined systematic error betweenthe predicted and measured tip locations in free space given aparticular instrument structure, a threshold may be utilized, beyondwhich error is considered an indicator of tissue contact. Depending uponthe cyclic motion pattern selected, the direction of contact between theinstrument and another object may also be detected by observing thedirectionality of error between predicted and measured instrumentposition.

Referring to FIG. 152, a distal tip of an instrument (519) is depictedhaving two vibratory devices (520). In one embodiment, one device is avibratory transmitter, such as a piezoelectric crystal adjacent amembrane, and the other device is a vibratory receiver comprising, forexample, a membrane adjacent another piezoelectric crystal. In anotherembodiment, both devices, a single device, or more than two devices maycomprise both transmitters and receivers. In free cavity space, theinstrument will vibrate more freely than it will when in mechanicalcontact with a tissue structure, and in this embodiment, the differenceis detected and logically interpreted as a tissue structure contactindicator.

Referring to FIGS. 153-155, another embodiment of a tissue contactsensing means is depicted wherein impedance monitoring through multiplepaths at multiple frequencies may be utilized as an indicator of tissuecontact. Conductivity measured through blood varies relatively littlewith frequency modulation, whereas conductivity does vary moresignificantly with frequency modulation when measured through a tissuestructure. By quickly switching frequencies and taking measurements atvarious frequencies, using, for example, a microprocessor, one can makea determination regarding contact with tissue or not based upon theassociated modulation in conductivity or impedance.

Such a technique may be combined with conductivity path modulation.Conventionally, impedance is measured between an instrument tipelectrode and a dispersive ground mounted, for example, upon the skin ofa patient's back. With such a configuration, conductivity increases, andimpedance decreases, when the instrument is in contact with, forexample, the heart wall. Another measurement path of interest isconductivity between an instrument tip electrode and another electrodeinside of the same chamber, but at a more proximal instrument location.As blood is relatively highly conductive, conductivity will be at amaximum when the tip electrode is not in contact with tissue, and willdecrease when the tip electrode touches a tissue wall, resulting inobscuring at least a portion of the tip electrode. Indeed, previousstudies have shown conductivity or impedance measurements take with sucha configuration can be utilized to predict contact before it actuallyoccurs, and that depth of tip electrode penetration may also bepredicted given the relationship between conductivity and obstruction ofthe tip electrode by tissue.

FIG. 153 depicts a further instrument embodiment (522) having a distaltip configured to facilitate such functionality. The instrument (522)has a tip electrode disposed distally, and four electrodes (524 a-d)disposed more proximally at corner positions to facilitate contact withtissue structures as the instrument is positioned adjacent a tissuestructure in a near parallel or tangential manner. FIG. 154 depicts theinstrument (522) adjacent a tissue structure (523) with reference to adispersive patch electrode (524) located upon the skin of a patient'sback. With such a configuration, impedance may be monitored between anypair of electrodes, with various frequencies, to provide a configurationcombining not only frequency modulation to detect tissue-electrodecontact, but also conductivity comparison path modulation to detecttissue-electrode contact.

Referring to FIG. 155, a schematic is depicted for utilizing fastswitching hardware, such as microprocessors, to collect data with eachof the pertinent combinations. Each cycle of acquisition through thevarious combinations yields impedance difference monitoring based uponpath switching and frequency switching, which may be compiled andlogically associated with determinations of tissue contact or not, andeven the location of the instrument which is predicted to be in contactwith tissue. Many other variations of electrode arrays may be utilizedin addition to the configuration depicted in FIG. 153, and frequency maybe modulated between more than three frequencies, as depicted in FIG.155, to produce additional data for each combination acquisition cycle.

FIGS. 156 and 157 depict another embodiment of a means for detectingcontact between an instrument electrode and a tissue structure, such asa cardiac wall. The electrocardiogram (“ECG”) signal acquired by aninstrument electrode positioned in free blood in the heart shows adiscernable signal, but from a signal processing perspective, is lesssharp and lower in amplitude due to the attenuation of high frequencysignal content, as compared with similar signals detected when theelectrode is in contact with a cardiac wall. When the ECG signal isdifferentiated with respect to time, the resulting differentiated signalhas higher amplitude when the electrode is in contact, as compared witha slower-rising curve for a not-in-contact scenario. In one embodiment,a microcontroller or digital signal processor (“DSP”) is utilized toperform sampling, differentiation, and analysis of acquired ECGwaveforms. In another embodiment, the shape of incoming ECG waveforms ismonitored to detect not only contact, but proximity to contact as thewaveform shape changes with proximity to the pertinent tissue structure.

Referring to FIG. 157, similar signal processing means are utilized tocompare an intracardiac ECG signal (527) with a body surface ECG signal(528), which essentially represents a superposition of the various ECGwaveforms from subportions of the heart. The fit between theintracardiac ECG signal is compared with the body surface ECG signal todetermine whether the intracardiac ECG signal does indeed appear to be aportion of the combined signal represented by the body surface ECGsignal. If the superposition match does not meet an experimentallydetermined threshold, the result is logically related to a state ofnon-contact between the intracardiac electrode and the heart wall tissuestructures.

When the intracardiac electrode is in contact with a particular wall ofthe heart, the intracardiac ECG signal is crisp, detailed, and fits wellinto a portion of the superimposed combined body surface ECG signal, asdepicted in FIG. 157. In another embodiment, the body surface ECG signalmay be split into, for example, four subportions, each of which may becompared in a similar manner to the intracardiac ECG signal for adetermination of not only contact, but also a confirmation of positionwithin the heart as associated with the four subportions. For example,the body surface ECG signal may be subdivided into four portionsrepresentative of the four chambers of the heart, or even four portionsof the same chamber.

In a generic form, the aforementioned “master following mode” may belogically configured to follow directly each command as it comes throughthe control system from the master input device. In one closed loopcontrol embodiment, however, a logic layer is configured to interpretdata incoming from a master input device and a localization system inlight of the integrated tissue structure model and certain systemsettings information pertinent to the particular procedure at hand, tomake modifications to commands forwarded to the master following andsubsequent main servo loop controls logic, resulting in movements of thephysical instrument.

Referring to FIGS. 158-160, some relatively simplistic examplesillustrate challenges addressed by interpreted master following. Theexemplary instrument embodiment depicted in each of these figurescomprises a localization device and a contact sensing device. Manycombinations or instrument componentry may be utilized with aninterpreted master following logic layer to provide an operator withenhanced navigation functionality, depending upon the functionalobjectives.

As shown in FIG. 158, an instrument (530) has a distal end carrying alocalization device (532) is positioned adjacent an irregular tissuewall which is represented in the system's visualization and controlsystems by a preferably three-dimensional tissue structure modelacquired utilizing one of the aforementioned modalities. Supposing thatthe operator's objective is to move the instrument distal tip asindicated in FIG. 158, an operator's preferred movement path dependsupon his preferred action in between the two locations. For example, ifthe operator merely wishes to touch the instrument (530) to the tissuewall in each location without contacting any tissue in between, theoperator may prefer a path of efficiency around the irregularity in thetissue structure, such as that depicted by a dashed line (531).Following this path, the operator may drive the instrument between therespective positions/locations.

Additionally or alternately, the operator may wish to lightly touch theinstrument (530) against the tissue structure and keep the instrument incontact as the instrument is driven between the locations depicted inFIG. 159 via a series of hops between the two locations, rather than aconstant dragging type of contact as described in the aforementionedembodiment. Further, in another embodiment, as depicted in FIG. 160, theoperator may wish to move the instrument between positions, whilemaintaining the instrument substantially normal to the tissue structurewall, perhaps due to the preferred orientation of a distal instrumentfeature, e.g., an electrode.

In addition, the operator may wish to have safety functionality builtinto the controls logic to, for example, prevent the instrument fromdamaging the subject tissue structures by excessively dragging along thetissue with an excessive load, overloading or overstressing a particularportion of a tissue structure with a concentrated load, or occupying aregion that may cause tissue damage, such as an active valve entrance.

Such operator objectives are addressed in various embodiments of aninterpreted master following logic layer interposed into the controlslogic. In one embodiment, interpreted master following interpretscommands that would normally lead to dragging along the tissue structuresurface as commands to execute a succession of smaller “hops” to andfrom the tissue structure surface, while logging each contact as a newpoint to add to the tissue structure surface model. Hops are preferablyexecuted by backing the instrument out the same trajectory it came intocontact with the tissue structure, then moving normally along the wallper the tissue structure model, and re-approaching with a similartrajectory. In addition to saving to memory each new XYZ surface point,in one embodiment. the system saves the trajectory of the instrumentwith which the contact was made by saving the localization orientationdata and control element tension commands to allow the operator tore-execute the same trajectory at a later time if so desired. By savingthe trajectories and new points of contact confirmation, a more detailedcontour map is formed from the tissue structure model, which may beutilized in the procedure and continually enhanced. The length of eachhop may be configured, as well as the length of non-contact distance inbetween each hop contact.

In one embodiment, interpreted master following performs a variety ofsafety checking steps to ensure that the operator does not accidentallydamage the subject tissue structure by driving into it or through itwith the instrument. For example, the controls logic may be configuredto disallow driving of the instrument beyond or into the subject tissuestructure, as determined utilizing a tissue structure model withlocalization data and/or contact sensing. Such a mode may be manuallyoverridden with an operator command in certain scenarios, for example,in order to purposefully puncture a tissue wall such as the septum atthe location of the fossa ovalis. In one embodiment, the controls logicmay be configured to prevent instrument electrode activation while theoperator is attempting to move the instrument, or may attempt to preventelectrode activation in the same location for more than a predeterminedtime or amount of energy delivered.

In another embodiment, interpreted master following assists the operatorin automating various clinical procedures. For example, where theinstrument comprises a distal ablation electrode, the controls may beconfigured to automatically fit a circular ablation pattern throughthree contact points selected by the operator. Further, an operator mayselect a hopping, intermittent electrode burning pattern toautomatically apply has he merely moves the master input devicelinearly. Haptics functionality may be utilized to provide the operatorwith various feedback to assist in clinical procedures. For example, ahaptic “groove” may be created along the insertion axis of theinstrument to assist the operator in driving the instrument with themaster input device. Further, previously selected points of desiredcontact may be haptically turned in to “gravity wells” to assist theoperator in directing the instrument to such locations.

A control system embodiment, such as described above, facilitatesprecision steerability of a catheter-based instrument in order toconduct a medical procedure. As an exemplary application, a myocardialablation procedure to address atrial fibrillation will now be describedwith reference to FIGS. 161-174.

Referring to FIG. 161, a standard atrial septal approach is depictedwith a robotically controlled guide catheter instrument (534) and sheathinstrument (535) passing through the inferior vena cava and into theright atrium. Referring to FIG. 162, an imaging device, such as anintracardiac echo (“ICE”) sonography catheter (536), is forwarded intothe right atrium to provide a field of view upon the interatrial septum.The guide instrument is driven to the septum wall, as shown in FIG. 163.Referring to FIGS. 164 and 165, the septum (537) may be crossed using aconventional technique of first puncturing the fossa ovalis locationwith a sharpened device (538), such as a needle or wire, passed throughthe working lumen of the guide instrument (534), then passing a dilator(539) over the sharpened device and withdrawing the sharpened device toleave the dilator (539), over which the guide instrument (534) may beadvanced, as shown in FIG. 166. It may be desirable in some embodimentsto pass an instrument arrangement through the working lumen of the guideinstrument comprising a needle positioned coaxially within a dilator, asis well known in conventional (i.e., non-robotic) septum crossingtechniques.

As shown in FIG. 167, subsequent to passing the guide instrument (534)across the septum (537), the guide instrument (534) may be utilized as adilator to insert the sheath instrument (535) across the septum (537),thereby providing both instruments (534, 535) access and/or a view intothe left atrium. It may be desirable to anchor the sheath instrument(535) in place just across the septum (537). For example, as shown inFIG. 168, an expanding structure such as a conventional balloon anchor(540) may be employed. As shown in FIG. 169, the guide instrument (534)may then be used to navigate inside the left atrium.

In one embodiment, a radio frequency (RF) ablation system is used withthe robotic catheter system to supply energy to perform myocardialtissue ablation procedures in order block undesirable conductionpathways within the wall of the left atrium and adjoining vessels (e.g.,pulmonary vein). By way of illustration, FIG. 170 depicts a system levelview of such arrangement, including an operator control station (2), acomputer (6), an instrument driver (16), a RF ablation energy controlunit (541), a guide instrument (543) and a working instrument (547).

In one embodiment, shown in FIG. 171, a robotically controlled guideinstrument (543), which may have an outer diameter of about 7 French,comprises an integrated ablation distal tip, and is passed through asheath instrument (535). In another embodiment, shown in FIG. 172, aworking instrument (547), in this instance an “off the shelf” ablationcatheter such as that sold under the trade name Blazer™ by BostonScientific Corporation, which may have an outer diameter of about 7French, is passed through the working lumen of the guide instrument(534), which itself is passed through a sheath instrument (535). In suchembodiments, the RF power may be supplied directly from the RF generatorto the ablation catheter handle. Alternatively, the power supply may becoupled to the ablation catheter via a controller integrated with therobotic guide instrument in order to provide addition safety features,e.g., automatic power shut-off under defined circumstances. In suchembodiments, only a small portion of the ablation catheter need beprotruded beyond the distal tip of the guide instrument to expose theablation electrodes, and the steering features which may be integratedinto the “off the shelf” ablation catheter may not be needed as a resultof the precision steerability provided by the robotically-controlledinstrumentation through which the ablation catheter is coaxiallypositioned. Alternatively, a greater portion of the ablation cathetermay be protruded beyond the distal tip of the guide instrument,preferably with the guide instrument held in a constant position by thesystem, and the manual steering functionality of the “off the shelf”ablation catheter may be utilized to place the distal portion of suchdevice in a desired location, utilizing feedback to the operator fromfluoroscopy, ultrasound, localization, or other real-time or nearreal-time systems. It will be appreciated by those skilled in the artthat many of types of other ablation catheters or other workinginstruments may be passed through the working lumen of the guideinstrument (534).

There are many well-known diagnostic or therapeutic distal end electrodeconfigurations of working instruments that may used in conjunction withthe guide instrument (534), such as those shown by way of non-limitingexample in FIGS. 173A-D. Other tip options include non-contact meanssuch as microwave or ultrasound energy (indicated by an “arrow” emittedfrom distal tip element (612) in FIG. 174A), optical laser energy(indicated by multiple “arrows” emitted from distal tip element (614) inFIG. 174B), a penetrating electrode or chemical/drug injection needle(element (616) in FIG. 174C), or mechanical grasper (element 618 in FIG.174D).

In another embodiment, the instrument may be navigated by “directvisualization” utilizing conventional fiberscope or CCD camera devices,preferably disposed within a distally-positioned viewing ballooncontaining a substantially clear fluid such as saline when in a bloodenvironment. In yet another embodiment, an infrared visualizationtechnology, such as those available from CardioOptics Corporation, maybe coupled to the instrument to provide direct visualization through ablood or similar medium without a viewing balloon or similar structure.In another embodiment wherein the instrument is navigated in a non-bloodspace, a viewing balloon need not be positioned to protect the cameradevice, and the camera lens or image intake may be positioned at thedistal tip of the instrument. Whether the direct visualization device isassisted by a balloon-like visualization structure or not, the devicepreferably is coupled to the instrument either by insertion through theworking lumen of an embodiment of the instrument, or integrated into oneof the walls comprising the elongate instrument.

Conventional sensors may be disposed at and/or around the distal tip ofthe instrument, such as those which comprise strain gages and/orpiezoelectric crystals. Also, more than one localization device may becoupled to the instrument along different positions of the instrument toallow for more complex monitoring of the position of the instrument.Such additional information may be utilized to help compensate for bodymovement or respiratory cycle related movement of tissues relative to abase coordinate system.

In still another embodiment of the tissue structure model acquisitionmodalities described above, including a contact sensor, the instrumentmay merely be driven around, in a planned fashion, or even at random,within a cavity to collect and store all points of contact to develop athree-dimensional model of the tissue structures. In a relatedembodiment, a rough model acquired utilizing a conventional imagingmodality such as ultrasound or fluoroscopy may be utilized as a startingpoint, and then additional points added, particularly at points ofinterest, such as pulmonary vein and valve locations within the leftatrium, utilizing a “tapping around” pattern with contact sensing togather more points and refine the model.

While multiple embodiments and variations of the many aspects of theinvention have been disclosed and described herein, such disclosure isprovided for purposes of illustration only.

What is claimed:
 1. A robotic medical instrument system, comprising: anoperator workstation comprising one or more displays, and one or moreinput devices; a controller operatively coupled to the operatorworkstation; an instrument driver operatively coupled to the controller,the instrument driver comprising one or more motors operatively coupledto an instrument interface; a mounting structure including configurablerevolute joint, the configurable revolute joint comprising acontrollable electronic brake, the mounting structure having a first endremovably attachable to an operating table, and a second end removablycoupled to the instrument driver, wherein the instrument driver isrotatable relative to the mounting structure; and an elongate flexibleguide instrument having a longitudinal axis and a base portionoperatively coupled to the instrument interface, wherein the controlleris configured to selectively actuate the one or more motors to therebyselectively move a distal end portion of the guide instrument inresponse to control signals generated, at least in part, by the one ormore input devices.
 2. The system of claim 1, wherein the instrumentdriver is rotatable relative to the mounting structure about a roll axisthat is substantially coincident with a roll axis of the guideinstrument about its longitudinal axis.
 3. The system of claim 1,wherein the instrument driver is rotatably coupled to the mountingstructure via a bearing structure.
 4. The system of claim 3, wherein theinstrument driver is controllably rotatable about the bearing structureabout a roll axis that is substantially coincident with a roll axis ofthe guide instrument about its longitudinal axis.
 5. The system of claim1, wherein the first end of the mounting structure is removablyattachable to an operating table via a railing to allow relativepositioning of the instrument driver along a length of the operatingtable.
 6. The system of claim 1, wherein the mounting structurecomprises a plurality of revolute joints.
 7. The system of claim 1,wherein the mounting structure is configurable to be selectively fixedin a position such that the instrument driver is substantially alignedwith a lengthwise dimension of the operating table.
 8. The system ofclaim 7, wherein the instrument interface is positioned on theinstrument driver such that, when the instrument driver is substantiallyaligned with the lengthwise dimension of the operating table, thelongitudinal axis of the instrument is also substantially aligned withthe lengthwise dimension of the operating table.
 9. A robotic medicalinstrument system, comprising: an operator workstation comprising one ormore displays, and one or more input devices; a controller operativelycoupled to the operator workstation; an instrument driver operativelycoupled to the controller and having proximal and distal portions, theinstrument driver distal portion comprising an instrument interface,with one or more motors operatively coupled to the instrument interface;a mounting structure, including a configurable revolute joint, theconfigurable revolute joint comprising a controllable electronic brake,having a first end removably attachable to an operating table, and asecond end coupled to the proximal portion of the instrument driver suchthat instrument driver is rotatable relative to the mounting structure;and an elongate flexible guide instrument having a longitudinal axis anda base portion operatively coupled to the instrument interface, whereinthe controller is configured to selectively actuate the one or moremotors to thereby selectively move a distal end portion of the guideinstrument in response to control signals generated, at least in part,by the one or more input devices.
 10. The system of claim 9, wherein theinstrument driver is rotatable relative to the mounting structure abouta roll axis that is substantially coincident with a roll axis of theguide instrument about its longitudinal axis.
 11. The system of claim 9,wherein the instrument driver is rotatably coupled to the mountingstructure via a bearing structure.
 12. The system of claim 11, whereinthe instrument driver is controllably rotatable about the bearingstructure about a roll axis that is substantially coincident with a rollaxis of the guide instrument about its longitudinal axis.
 13. The systemof claim 9, wherein the mounting structure comprises an arcuate-shapedstructural member configured to position the instrument driveroverlaying the operating table.
 14. A robotic medical instrument system,comprising: an operator workstation comprising one or more displays, andone or more input devices; a controller operatively coupled to theoperator workstation; an instrument driver operatively coupled to thecontroller, the instrument driver comprising one or more motorsoperatively coupled to an instrument interface; a mounting structure,including a configurable revolute joint, the configurable revolute jointcomprising a controllable electronic brake, comprising means toselectively position the instrument driver relative to an operatingtable, wherein the instrument driver is coupled to the mountingstructure such that the instrument driver is rotatable relative to themounting structure; and an elongate flexible guide instrument having alongitudinal axis and a base portion operatively coupled to theinstrument interface, wherein the controller is configured toselectively actuate the one or more motors to thereby selectively move adistal end portion of the guide instrument in response to controlsignals generated, at least in part, by the one or more input devices.15. The system of claim 14, wherein the instrument driver is rotatablerelative to the mounting structure about a roll axis that issubstantially coincident with a roll axis of the guide instrument aboutits longitudinal axis.
 16. The system of claim 14, wherein the mountingstructure is configurable to be selectively fixed in a position suchthat the instrument driver is substantially aligned with a lengthwisedimension of the operating table, and wherein the instrument interfaceis positioned on the instrument driver such that, when the instrumentdriver is substantially aligned with the lengthwise dimension of theoperating table, the longitudinal axis of the instrument is alsosubstantially aligned with the lengthwise dimension of the operatingtable.